Articles Index

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.

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.

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.

Deleting Database Tables with the DROP Command
The DROP command allows us to remove entire database objects from our database.

Creating Databases and Tables In SQL
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.

Inserting Data with the SQL INSERT Command
The INSERT command in SQL is used to add records to an existing table. Returning to the personal_info example from the previous section, let's imagine that our HR department needs to add a new employee to their database.

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.

Classifying Results with SQL CASE Statements
SQL includes a CASE statement that allows you to return varying results based upon the evaluation of expressions. You can use a CASE statement anywhere within a SQL statement that you would normally include an expression. CASE statements are often found in SELECT, UPDATE and DELETE statements as well as WHERE and IN clauses.

Using the GROUP BY Clause to Group SQL Query Results
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.

Joining Multiple Tables with SQL Inner Join Statements
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.

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.

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.

SQL Fundamentals
Would you like to learn SQL? This tutorial will introduce you to the basics.