1. Computing

Databases: Most Popular Articles

These articles are the most popular over the last month.
The Basics of Normalizing a Database
Database normalization can save storage space and ensure the consistency of your data. Learn the basics in this introductory article.
Primary Key Definition: What is a Primary Key?
What is a primary key? Find out here!
What is the domain of a database? Find out here!
What is a Database?
Databases are designed to offer an organized mechanism for storing, managing and retrieving information. They do so through the use of tables. If you’re familiar with spreadsheets like Microsoft Excel, you’re probably already accustomed to storing data in tabular form. It’s not much of a stretch to make the leap from spreadsheets to databases.
A Quick Guide to Using Inner Joins in SQL to...
You can use SQL JOIN statements to combine data from three or more tables. In an earlier article, we took a look at using inner joins and outer joins to combine data from two different tables. In many cases, you’ll want to take this a step further and combine data from three or more tables. Let's take a look at the SQL statements that allow you to accomplish this goal for an inner join.
How to Understand an Entity-Relationship Diagram
What is a database? Find out here!
Referential Integrity
What is Referential Integrity? Find out in our database glossary!
Normalizing Your Database: Third Normal Form...
In our first article, we looked at the basic requirements of 3NF. Here they are again to refresh your memory: meet the requirements of 1NF and 2NF and remove columns that are not fully dependent upon the primary key.
Facts vs. Dimensions
Facts and dimensions form the core of any business intelligence effort. These tables contain the basic data used to conduct detailed analyses and derive business value. In this article we take a look at the development and use of facts and dimensions for business intelligence.
The Top 6 Books Every SQL Enthusiast Should Read
Looking for a book to help you get started with Strucutred Query Language? Need a new reference book for your shelf? Check out my favorite SQL books.
A Quick Guide to Database Normalizing with...
In this article, we begin our look at the first of three major normal forms -- first normal form (otherwise known as 1NF).
Retrieving Data from Multiple Tables with SQL...
SQL joins allow you to retrieve data from multiple database tables. Your About.com Guide to Databases provides a comprehensive introduction.
The Beginner's Guide to Databases, SQL, and...
Are you new to the world of databases? Wondering where to get started? In this series of articles, we introduce you to the basics of database technology and help you get started in this exciting field.
Access File Formats: ACCDB vs MDB
The release of Access 2007 brings a new file format. The MDB database files we’ve known for over a decade are now slated to become historical relics. While Access 2007 continues to support MDB databases for backwards compatibility purposes, Microsoft has now introduced the new ACCDB file format as the future standard. Wondering if you should begin using the ACCDB format?
Basic Keys That Make Database Management Easy
As you may already know, databases use tables to organize information. Each table consists of a number of rows, each of which corresponds to a single database record. So, how do databases keep all of these records straight? It’s through the use of keys.
Microsoft Access Fundamentals
Want to learn how to use Microsoft Access? Find out on the About.com Databases site!
How to Build a New Access Database in SQL
In this series of Microsoft Access tutorials, we follow the database administrators for Patrick's Widgets as they build a Microsoft Access database from the ground up.
A Quick Guide to Understanding Database...
Database dependencies are a topic that often confuses both students and database professionals alike. Fortunately, they are not that complicated and can best be illustrated through the use of a number of examples. In this article, we examine common database dependency types.
MCTS 70-432 SQL Server Practice Exam
Free Practice Test for Microsoft Exam 70-432 Microsoft SQL Server 2008, Implementation and Maintenance
Database Relationships: An Introduction To...
Relationships allow you to describe the connections between different database tables in powerful ways. Once you’ve described the relationships between your tables, you can later leverage that information to perform powerful cross-table queries, known as joins.
Foreign Key
What is a foreign key? Find out here!
Deleting Data from an SQL Table
The SQL DELETE command allows the removal of some or all of the data stored in a relational database table.
The Quick Way to Import and Export SQL Server...
The bulk copy (bcp) command of Microsoft SQL Server provides you with the ability to insert large numbers of records directly from the command line. In addition to being a great tool for command-line aficionados, bcp is a powerful tool for those seeking to insert data into a SQL Server database from within a batch file or other programmatic method.
Top Five Things Beginners Need to Know About...
Just getting started with databases? Here's a rundown of the top things that I wish I knew before I got started in the field. These facts are guaranteed to make your life easier!
Retrieving Data with SQL Queries: Introducing...
Learn to retrieve information from your database with the SQL SELECT statement. Your About.com Guide to Databases provides a thorough introduction.
How to Put a Database in Second Normal Form (2NF)
Second Normal Form allows you to enhance the normalization of your database. In this article, we explore the requirements of 2NF and the process of normalizing your database.
Functional Dependency
What is a functional dependency? Find out here!
SQL Fundamentals
Would you like to learn SQL? This tutorial will introduce you to the basics.
Database Software Options
You've finally buckled down and decided that it's time to purchase a database solution for your home or business. What type of database do you need? It's actually a simple matter of deciding what features you need and choosing a product that meets your requirements and doesn't cause too much pain in your pocketbook.
Choosing a Primary Key
Databases depend upon keys to store, sort and compare records. If you’ve been around databases for a while, you’ve probably heard about many different types of keys – primary keys, candidate keys, and foreign keys. When you create a new database table, you’re asked to select one primary key that will uniquely identify records stored in that table.
Converting an Access Database to SQL Server
Is your Access database growing too large or unwieldy? Perhaps you need to allow more robust multiuser access to the database? Converting your Access database to Microsoft SQL Server might be the solution you’re trying to find. Fortunately, Microsoft provides an Upsizing Wizard in Access that makes it easy to convert your database. In this tutorial, we walk through the process of converting your database.
Entity-Relationship Diagrams
Entity Relationship diagrams (also known as E-R or ER diagrams) provide database designers with a valuable tool for modeling the relationships between database entities in a clear, precise format. This industry standard approach uses a series of block shapes and lines to describe the structure of a database in a manner understandable to all database professionals. Many database software packages, including Microsoft Access, SQL Server, and Oracle, provide automated methods to quickly create E-R diagrams from existing databases.
Starting a Career in Databases
Looking for a job in the database field? This article provides the advice you need to get started.
How To Install the Northwind Sample Database in...
The Northwind database contains some great sample tables, queries, reports and other database features. Here's how to install it.
SQL Server Stored Procedures
Microsoft SQL Server provides the stored procedure mechanism to simplify the database development process by grouping Transact-SQL statements into manageable blocks.
Creating a Simple Query in Microsoft Access
Want to learn how to create a query in Microsoft Access? Find out on the About.com Databases site!
Building an Access Database in Office 365
Looking for an easy way to move your Microsoft Access database to the cloud? Microsoft’s Office 365 service provides a central location where you can store and manipulate your Microsoft Access databases. This service has multiple benefits including leveraging Microsoft’s highly available environment to protect your data and enabling multiuser access to your database in a scalable fashion. In this article, we look at the process of moving your Microsoft Access database to Office 365.
Query Definition
What is a query? Find out here!
Choosing a Database for Your Organization
Database management systems (or DBMSs) can be divided into two categories -- desktop databases and server databases. Generally speaking, desktop databases are oriented toward single-user applications and reside on standard personal computers (hence the term desktop). Server databases contain mechanisms to ensure the reliability and consistency of data and are geared toward multi-user applications.
Data Definition Language
Would you like to learn SQL? This tutorial will introduce you to the basics. Page 2.
An Easy Guide to Creating Databases and Tables...
Learn to create databases and tables using the Structured Query Language (SQL) in this step-by-step tutorial from your About.com Guide to Databases.
Transaction Log Shrinking and Truncation in SQL...
The transaction log plays a critical role in a SQL Server database: it maintains an ongoing record of database activity crucial for the restoration of recent data in the event of a disaster. However, this benefit comes at a cost: the transaction log can consume a substantial amount of space in an active database. SQL Server provides two actions designed to counterbalance these large space requirements: transaction log truncation and log file shrinking.
Creating Forms in Microsoft Access
Learn how to create a simple form in Microsoft Access. This tutorial walks you through the process step-by-step!
Creating Database Relationships in Access
Join us as we walk through the process of creating database relationships in Microsoft Access.
The ACID Model
All database management systems should share four characteristics: Atomicity, Consistency, Isolation and Durability.
Candidate Key
What is a Candidate Key? Find out here!
Partitioning a SQL Server Database Table
Looking to optimize the performance of your SQL Server database? If your database contains very large tables, you may benefit from partitioning those tables onto separate filegroups. This technology, introduced in SQL Server 2005, allows you to spread data onto different physical disks, leveraging the concurrent performance of those disks to optimize query performance.
Self-Joins in SQL
You can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table. These joins allow you to retrieve related records from the same table.
Counting Values in a Database Table with the...
The COUNT() function in SQL allows you to count database records based upon a variety of criteria. You can use it to count all records in a table, count unique values in a column or count the number of times records occur that meet certain criteria. This tutorial takes a brief look at each of these scenarios.
ZIP Code Database
This free Access database of ZIP codes provides database designers with a valuable tool to assist in mapping ZIP codes to a city/state pair and even provides the latitude and longitude of that location.
Creating Dynamic Web Pages with Microsoft Access
Want to create dynamic, server-generated HTML from your Access database? This step-by-step tutorial will walk you through the process.
Top 5 Desktop Databases
Desktop databases offer simple, flexible solutions for data storage and retrieval. They're often quite sufficient to meet uncomplicated database requirements for both small and large organizations. If you're not sure if a desktop database is right for you, try reading the Choosing a Database series of articles which cover both desktop and server databases in depth
Database Management System
A database management system (DBMS) is the software that allows a computer to perform database functions of storing, retrieving, adding, deleting and modifying data.
Summarizing Data with CUBE and ROLLUP
SQL's CUBE and ROLLUP commands allow for the efficient summarization of data. Learn how to use them here!
Boyce-Codd Normal Form (BCNF)
What is Boyce-Codd Normal Form (BCNF)? Find out here!
Microsoft Access Reports Tutorial
Would you like to create professional-looking reports from your Microsoft Access database with the click of a mouse? Follow along as we walk through the simple process of designing a reusable report.
Converting an Excel Spreadsheet to an Access...
Are you ready to convert your unwieldy Excel spreadsheet to a flexible Access database? Let us walk you through the process!
Data Manipulation Language
Would you like to learn SQL? This tutorial will introduce you to the basics. Page 3.
How To Add a Date or Time Stamp to an Access...
There are many applications where you may wish to add a date/time stamp to each record, identifying the time that the record was added to the database. It’s easy to do this in Microsoft Access using the Now() function. In this tutorial, I explain the process step-by-step.
Create a Microsoft Access Database Using a...
Microsoft provides quite a few prebuilt database templates to assist you in jumpstarting your database development process. In this tutorial, we'll walk through the process of creating an Access database using these templates.
Pattern Matching in SQL Server Queries
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JOIN operations allow us to combine data from multiple tables. Learn how these operations treat the NULL value.
Structured Query Language (SQL)
Most large-scale databases use the Structured Query Language (SQL) to define all user and administrator interactions. This language offers a flexible interface for databases of all shapes and sizes.
Foreign Keys in Microsoft SQL Server
One of the most important concepts in databases is creating relationships between database tables. These relationships provide a mechanism for linking data stored in multiple tables and retrieving it in an efficient fashion. In order to create a link between two tables, you must specify a foreign key in one table that references a column in another table.
Should I Normalize My Database?
Database normalization is one of the sacred cows of application development. Every undergraduate programming course you’ve taken or book you’ve read likely preaches about the importance of normalizing databases in an almost religious fashion. You’re made to feel like failure to normalize a database is tantamount to violating one of the laws of the universe. It’s time to challenge that truism. Sometimes it’s OK to denormalize your database
Installing MySQL on Windows 7
The MySQL database server is one of the most popular open source databases in the world. Although administrators typically install MySQL on a server operating system, it’s certainly possible to install it on a desktop operating system like Windows 7. Once you do so, you’ll have the tremendous power of the flexible MySQL relational database available to you for free. It’s an extremely useful database for both developers and system administrators. Installing MySQL on Windows 7 is an especially valuable tool for those seeking to learn database administration but lack access to a server of their own. Here’s a step-by-step walkthrough of the process.
Microsoft Access Sample Database: Countries,...
This Microsoft Access sample database provides tables containing information on the world's countries, cities and provinces. It is used to illustrate examples for a number of the articles on the About Databases site and also provides a good sample for students, professionals and others who are learning Microsoft Access.
Using the GROUP BY Clause to Group SQL Query...
You may use basic SQL queries to retrieve data from a database but this often doesn’t provide enough intelligence to meet business requirements. SQL also provides you with the ability to group query results based upon row-level attributes in order to apply aggregate functions using the GROUP BY clause.
What is a superkey? Find out here!
Aggregate Functions in SQL
Summarize data with SQL's SUM, AVG, MIN, MAX and COUNT functions. Your About.com Guide to Databases walks you through the process.
Data Control Language (DCL)
The Data Control Language (DCL) is a subset of the Structured Query Lanaguge (SQL) that allows database administrators to configure security access to relational databases. It complements the Data Definition Language (DDL), which is used to add and delete database objects, and the Data Manipulation Language (DML), which is used to retrieve, insert and modify the contents of a database.
How To View and Edit SQL in Microsoft Access
Did you know that you can view and edit the SQL statements that drive every Microsoft Access database query? In this article, we take a look at the process of accessing the underlying SQL code and tweaking it to perfect Access queries.
Automating Database Administration with SQL...
Create a New SQL Server Agent Job. Page 3.
Testing For SQL Injection Vulnerabilities
SQL Injection attacks pose tremendous risks to web applications that depend upon a database backend to generate dynamic content. In this type of attack, hackers manipulate a web application in an attempt to inject their own SQL commands into those issued by the database. In this article, we take a look at several ways you can test your web applications to determine whether they're vulnerable to SQL Injection attacks.
Microsoft Access Genealogy Database Template
Are you interested in tracing your family roots but don’t have a good place to store all of your genealogical information? While there are several full-featured family tree software packages on the market, you can also use a free Microsoft Access template to create your own genealogy database on your computer. Microsoft’s already done most of the work for you, so there is no programming knowledge needed to get started.
Multivalued Dependency
What is a multivalued dependency? Find out here!
SQL Server Replication
Microsoft SQL Server provides a robust replication facility to distribute and update data in a decentralized fashion.
Choosing a SQL Server Authentication Mode
Microsoft SQL Server 2008 offers administrators two choices of performing user authentication: Windows authentication mode and mixed authentication mode. Making the proper choice affects both the security and maintenance of your organization’s databases.
How To Include Attachments in an Access Database
Microsoft Access allows you to include attachments in database tables. You may store photos, graphics, documents and other files in your Access database using Microsoft's Object Linking and Embedding (OLE) technology. Database attachments are a new feature in Access 2007.
Using TRY…CATCH to Handle SQL Server Errors
The TRY…CATCH statement in Transact-SQL allows you to detect and handle error conditions gracefully within your database applications. This statement is the cornerstone of SQL Server error handling and is an extremely important part of developing robust database applications.
Creating Forms in Microsoft Access 2013
Although Access provides a convenient spreadsheet-style datasheet view for entering data, it isn’t always an appropriate tool for every data entry situation. If you’re working with users you don’t want to expose to the inner workings of Access, you may choose to use Access forms to create a more user-friendly experience. In this tutorial, we’ll walk through the process of creating an Access form.
Transitive Dependency
What is a transitive dependency? Find out here!
Sample Excel Document
Sample Excel Document. Databases.
Creating an Access Database from Scratch
In an earlier article, we reviewed the process for creating an Access database from a template. While this is certainly an agreeable, easy approach to building a database, there isn’t always a template available that meets your needs. In this article, we review the process for creating an Access database from scratch.
Databases Glossary
Glossary of database related terms, including definitions, explanations, examples, suggested reading, and other resources.
SQL Server Recovery Models
SQL Server provides three different recovery models that allow you to specify the way SQL Server manages log files and prepares your enterprise for a disaster. Each of these models represents a different approach to balancing the tradeoff between conserving disk space and providing for granular disaster recovery options.
JOIN Statements
JOIN statements allow you to combine multiple tables in powerful ways. Page 4.
What is SQL?
The Structured Query Language (SQL) is the set of instructions used to interact with a relational database. In fact, SQL is the only language that most databases actually understand. Whenever you interact with such a database, the software translates your commands (whether they are mouse clicks or form entries) into SQL statement that the database knows how to interpret.
Trivial Functional Dependency
The definition of trivial functional dependency in relational database theory, along with an example and some further reading.
Exporting Access Tables to Excel
Microsoft Access allows you to export data to a variety of formats for sharing and analysis. In this tutorial, we walk through the process of exporting an Access table to an Excel workbook.
How To Create a Trace with SQL Server Profiler
Traces allow you to track the specific actions performed against a SQL Server databases. They provide valuable information for troubleshooting database issues and tuning database engine performance. In this tutorial, we walk through the process of creating a SQL Server Trace with SQL Server Profiler, step-by-step.
Microsoft Access User-Level Security Tutorial
If you’re a Microsoft Office power user, you might be familiar with the encryption features of Word, PowerPoint and Excel. These programs all allow file owners to easily apply encryption. Unfortunately, Microsoft Access doesn’t offer similar functionality, but it still has relatively powerful security functionality. In this article, we’ll take a look at Microsoft Access user-level security, a feature that lets you specify the level of access to grant each individual user of your database.
SQL Server Administration (70-228) Practice Exam
Looking to prove your SQL Server Administration mettle? This quiz will help you prepare for Microsoft's 70-228 exam: Installing, Configuring, and Administering Microsoft SQL Server 2000 Enterprise Edition. This is a critical step toward earning your Microsoft Certified Database Administrator credential.
Who Leads the RDBMS Pack?
According to most sources, Microsoft is rapidly gaining market share in the RDBMS arena. Have they finally surpassed Oracle? Read the latest results!
UNIQUE Constraints in Microsoft SQL Server
UNIQUE constraints allow SQL Server administrators to specify that a column may not contain duplicate values. When you create a new UNIQUE constraint, SQL Server checks the column in question to determine whether it contains any duplicate values. If the table contains preexisting duplicates, the constraint creation command fails. Similarly, once you have a UNIQUE constraint on a column, attempts to add or modify data that would cause duplicates to exist also fail.
MySQL Stored Procedures
With the release of MySQL 5.0, the popular open source database platform added one of the most long-awaited features: the ability to use stored procedures. Long a staple of commercial database systems, such as Microsoft SQL Server and Oracle, stored procedures provide database developers with a powerful tool.
Creating Relationships in Access
Join us as we walk through the process of creating database relationships in Microsoft Access.
Modifying a Query in Microsoft Access
Want to learn how to modify a query in Microsoft Access? Find out on the About.com Databases site!
Combining Query Results with the UNION Command
SQL’s UNION command allows you to combine the results of two or more database queries that are not necessarily linked through a database relationship. For example, imagine that you have a school database and wish to use it to create a master contact list for all students, faculty and staff. Looking at your database, you discover that the records corresponding to each of these constituencies appears in separate database tables.
Database Certifications
Popular database certifications are always in demand, whether it's Microsoft's MCTS or MCITP, Oracle's OCA, OCP and OCM or MySql's CMA, CMDEV and CMDBA. Are you a database professional seeking to polish your resume in the hopes of landing a better gig? Database vendors offer a variety of professional certification programs that can help you advance your career while gaining valuable technical skills.
SQLCMD Step-by-Step
Microsoft SQL Server provides users with a variety of rich graphical user interfaces to retrieve and manipulate data and configure SQL Server databases. However, sometimes it’s just easier to work from the old-fashioned command line. Whether you’re looking for a quick-and-dirty way to execute a SQL query or wish to include SQL statements in a Windows script file, SQLCMD allows you to meet your goal.
Full Functional Dependency
What is a full functional dependency? Find out here!
Using Self-Joins in SQL
Did you know that you can use a self-join to simplify nested SQL queries where the inner and outer queries reference the same table? Let's take a look at an example.
All About NULL Values
Users new to the world of databases are often confused by a special value particular to our field – the NULL value. Read about the proper uses of NULL in this article.
Creating Relationships
In the seventh installment of our Building an Access Database From the Ground Up series, we create relationships between our tables to finish implementing our relational model.
Installing MySQL on Mac OS X 10.7 Lion
The MySQL database server is one of the most popular open source databases in the world. Although there is not yet an official package for installing it on the latest version of the Macintosh operating system (Mac OS X 10.7, codenamed Lion), it is possible to install the database on such a system using the package designed for Mac OS X 10.6. Here’s a step-by-step walkthrough of the process.
Database Naming Rules
It’s very tempting to simply come up with something off the top of your head and run with it, but that’s not a great practice. Either you or your successors will curse the difficult field names you created down the road. In this article, I offer my advice on creating logical, consistent names for database fields, tables, reports, stored procedures and other objects.
Importing Bulk Data into SQL Server
SQL Server provides fourmethods you can use when you need to insert large quantities of data into a SQL Server database. These automated techniques will help you insert data from the results of a SQL query, a text file or another database.
Stored Procedures vs. User Defined Functions in...
SQL Server user-defined functions and stored procedures offer similar functionality. Both allow you to create bundles of SQL statements that are stored on the server for future use. This offers you a tremendous efficiency benefit, as you can save programming time by...
Creating a Simple Query in Access 2013
Have you ever wanted to combine information from multiple tables in your database in an efficient manner? Microsoft Access 2013 offers a powerful query function with an easy-to-learn interface that makes it a snap to extract exactly the information you need from your database. In this tutorial we'll explore the creation of a simple query.
Oracle Definition
What is Oracle? Find out here! Databases.
Database Instance
Looking for a definition of a database instance? Look no further!
Structured Query Language Frequently Asked...
Looking for advice on using the Structured Query Language? The About Databases SQL FAQ provides answers to the most frequently asked questions about SQL and databases.
An attribute, when in regards to databases, deals with single data in an object. It is one of the basic terms used in SQL.
What is a determinant? Find out here!
Data Input Via Forms
Part VIII of our tutorial introduces you to the concept of Access forms to input and modify data.
Installing MySQL on Windows 8
The MySQL database server is one of the most popular open source databases in the world. Although administrators typically install MySQL on a server operating system, it’s certainly possible to install it on a desktop operating system like Windows 7. Once you do so, you’ll have the tremendous power of the flexible MySQL relational database available to you for free. It’s an extremely useful database for both developers and system administrators. Installing MySQL on Windows 7 is an especially valuable tool for those seeking to learn database administration but lack access to a server of their own. Here’s a step-by-step walkthrough of the process.
Database Relationships
Looking for a definition of a database relationship? Check out the About Databases glossary definition!
Sample Excel Spreadsheet
This sample Excel spreadsheet provides a starting point for our Microsoft Access tutorials.
Selecting Data Within Ranges in SQL
The Structured Query Language (SQL)provides database users with the ability to create customized queries to extract information from databases. In an earlier article, we explored extracting information from a database using SQL SELECT queries. Let's expand upon that discussion and explore how you can perform advanced queries to retrieve data that matches specific conditions.
How To Compact and Repair an Access Database
Over time, Microsoft Access databases grow in size and unnecessarily use disk space. Additionally, repeated modifications to the database file may result in data corruption. Therefore, it's a good idea to periodically run the compact and repair database tool to ensure the consistency of your data.
Introduction to Pivot Tables
If you’re looking for some of the flexible query power of a database but don’t want to mess with relational database design, pivot tables may be just the technology you need. Chances are you’re already using one of the popular spreadsheet packages that include this technology, such as Microsoft Excel or the free Google Spreadsheets package.
Splitting an Access Database, Step by Step
Oftentimes, you wish to share data with users in your organization who may, in turn, wish to create their own forms and reports. While you may want them to have the ability to view and/or update your data, you may not wish them to modify the interface you use to work with the data yourself. Fortunately, Microsoft Access provides the ability to split a database into front-end and back-end components. You can safely share data with other users while keeping your interface private.
Sample Excel Document for Pivot Tables
This sample Excel document contains student course registration data for use in generating pivot tables. It should be used in conjunction with the Creating Pivot Tables in Excel 2010 tutorial found on this site.
Microsoft Access 2013 Fundamentals
Are you overwhelmed by the large quantities of data that need to be tracked in your organization? Perhaps you're currently using a paper filing system, text documents or a spreadsheet to keep track of your critical information. If you're searching for a more flexible data management system, a database might be just the salvation you're looking for and Microsoft Access 2013 provides an excellent option.
Second Normal Form (2NF) - Databases Glossary
What is Second Normal Form? Find out here!: acme widgets fred flintstone abc corporation john doe two tables
HIPAA in a Nutshell
The Health Insurance Portability and Accountability Act of 1996 (HIPAA) places a large regulatory burden on organizations that deal with certain types of health-related information. We're now only a couple of weeks away from the compliance deadline for the Security Rule. Are you ready for April 21st?
Binary Data Types in SQL Server
Binary data types allow you to store any type of binary data, including entire files of up to 2GB. They include binary, varbinary, image and bit.
k-means Clustering
k-means clustering is a data mining/machine learning algorithm used to cluster observations into groups of related observations without any prior knowledge of those relationships. The k-means algorithm is one of the simplest clustering techniques and it is commonly used in medical imaging, biometrics and related fields.
Controlling Data Access with Views
Database views allow you to easily reduce the complexity of the end user experience and limit their ability to access data contained in database tables by limiting the data presented to the end user. Essentially, a view uses the results of a database query to dynamically populate the contents of an artificial database table.
Creating Tables in Microsoft SQL Server
SQL Server databases rely upon tables to store data. In this tutorial, we'll explore the process of designing and implementing a database table in Microsoft SQL Server.
How To Back Up a Microsoft Access Database
Backing up your Microsoft Access databases is an important part of protecting your critical data. In this tutorial, we walk through the process of backing up an Access database, step-by-ste.
Data Mining: An Introduction
Data mining allows you to find the needles hidden in your haystacks of data. Learn how to use these advanced techniques to meet your business objectives.
What is a database schema? Find out here!
Date and Time Data Types in SQL Server
The date and time SQL Server data types are used to store calendar information. They include the datetime, smalldatetime and timestamp variables.
Backing up an 2013 Access Database
Backing up your Access 2013 database is an important step to preserve the integrity and availability of your important data. In this tutorial, we walk through the process of backing up an Access 2013 database, step-by-step.
The DISTINCT keyword in SQL allows you to select only those records that contain unique values for the columns requested in a SELECT statement. Duplicate values are ignored and only displayed once.
Input Masks in Microsoft Access 2013
Do your databases contain fields where users have entered a mess of information in a variety of different formats? Microsoft Access input masks may help you alleiviate this inconsistency in your desktop databases. Input masks allow you to specify the format of allowable user input, preventing users from entering information in a form that does not meet your data quality requirements.
MCTS 70-433 SQL Server Practice Exam
Free Practice Test for Microsoft Exam 70-433 Microsoft SQL Server 2008 Database Development Welcome to
Third Normal Form (3NF) - Databases Glossary
What is Third Normal Form? Find out here!: state zip code database designers abc corporation city state zip columbia md 21046
Retreiving Data with the SELECT Statement
The SELECT command is the most commonly used command in SQL. It allows database users to retrieve the specific information they desire from an operational database.
Introduction to SQL
The Structured Query Language (SQL) is the language of databases. All modern relational databases, including Access, FileMaker Pro, Microsoft SQL Server and Oracle use SQL as their basic building block. In fact, it’s often the only way that you can truly interact with the database itself.
NOT NULL Constraints in Microsoft SQL Server
NOT NULL constraints in Microsoft SQL Server allow you to specify that a column may not contain NULL values. When you create a new NOT NULL constraint on a database column, SQL Server checks the column’s current contents for any NULL values. If the column currently contains NULL values, the constraint creation fails. Otherwise, SQL Server adds the NOT NULL constraint and any future INSERT or UPDATE commands that would cause the existence of a NULL value fail.
Access Controls in SQL
SQL joins allow you to retrieve data from multiple database tables. Your About.com Guide to Databases provides a comprehensive introduction. Page 2.
SQL Server in Amazon Web Services
If you're seeking an inexpensive way to run a SQL Server database in the cloud, you might want to consider using the free tier of Amazon Web Services. AWS offers free limited use of a SQL Server Express database server for one year and is extremely easy to get up and running.
Creating a SQL Server Database Maintenance Plan
Database Maintenance Plans allow you to automate many database administration tasks in Microsoft SQL Server. You can create maintenance plans using an easy wizard-based process without any knowledge of Transact-SQL.
Encrypting Access 2013 Databases
Password protecting an Access database allows you to protect your sensitive data from prying eyes. Encrypted databases require a password to open. Users attempting to open the database without the correct password will be denied access. Additionally, users attempting to directly access the database’s ACCDB file will not be able to view any of the data contained within it, as the encryption obscures the data from view by those without the proper password.
Introduction to NoSQL
The NoSQL movement is changing the way we think about databases. Instead of requiring that database developers follow the rigid principles of the ACID model, NoSQL allows a great deal of flexibility that provides a tremendous efficiency boost. This comes, however, at the cost of reduced enforcement of traditional database constraints.
Publishing Access Data on the Web
Would you like to share your Access reports with the web? This step-by-step tutorial will walk you through the process.
One-to-Many Relationships
Looking for a definition of one-to-many database relationships? Read our definition in the About Databases glossary!

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