John Paul Ashenberger's
SQL introduction articles

John Paul Ashenberger's SQL introduction articles (the data for this list is collected and time-reordered from

  • What's the Big Deal about SQL?  Oct. 20, 2000
    SQL, the Structured English Query Language, is a standard for building relational databases. In this short introduction, author JPA explains relational databases and offers a history of the development and implementation of SQL.

  • Getting Started with SQL Oct. 20, 2000
    In the second half of his inaugural column, JPA introduces us to several good SQL learning tools and begins to define database terms.  

  • Introducing SELECT Oct. 27, 2000
    The SELECT command helps you find the data in your database. Here's a hands-on tutorial on how it works. 

  • Filtering SELECTed Data with WHERE Nov. 3, 2000
    SQL databases can be filtered by virtually any set of criteria using a single clause. This week, JPA shows us how to use the SELECT command to return subsets of data. 

  • INSERTing Data Nov. 10, 2000
    We've spent a fair amount of time discussing how to get data out of MySQL. But can you enter data directly into this database? You can using the INSERT command. 

  • UPDATE that Data! Dec. 22, 2000
    Now that you have your data in MySQL, how do you change it? We'll show you step by step. 

  • DELETE Tips and Tricks Dec. 29, 2000
    This week JPA discusses the most dangerous of the core SQL statements: DELETE. Proceed with caution. 

  • Where to Use WHERE Jan. 5, 2001
    We're continuing our exploration of the WHERE clause by digging a little deeper into its capabilities to see what it can really do. 

  • Using Functions Jan. 12, 2001
    JPA continues his SQL tutorial with one of the most useful but most frustrating areas of SQL: built-in functions.  

  • Aggregate Functions Jan. 30, 2001
    JPA looks at a specific class of SQL functions that operate on entire columns of data instead of discrete values -- the aggregate functions.  

  • Controlling Data Display with ORDER BY Feb. 13, 2001
    This week, JPA revisits the ORDER BY clause to help you control the display of your MySQL data.  

  • Group By Feb. 23, 2001
    The GROUP BY clause is the next step after mastering ORDER BY. JPA shows you how to combine database records into a single record to calculate an aggregate function.  

  • The "Key" to Good SQL Mar. 6, 2001
    Database "keys" help eliminate confusion among records. Here's how to best incorporate these essential identifiers in your database. 

  • Good Relations Mar. 13, 2001
    JPA looks at how keys are used to construct relationships between tables in a relational database.  

  • Types of Relationships Mar. 20, 2001
    How well are your database tables communicating with one another? This week John Paul discusses three key relationships: one to one, one to many, and many to many. 

  • JOINed at the Hip May. 24, 2001
    The JOIN clause is probably one of the most used -- as well as one of the most confusing -- facets of SQL. JPA introduces the JOIN clause.  

  • More on JOINS Jun. 1, 2001
    The exploration into JOIN statements continues with a look at INNER JOIN, the most commonly used SQL join.  

  • Types of JOINs Jun. 15, 2001
    A look at what's going on behind the scenes when you perform a "join" in MySQL. JPA uses the cross join as an example of how joins work in general. 

  • The Outer Limits of SQL JOINs Jun. 27, 2001
    In the last column, JPA showed you how to use inner joins and cross joins. This week he tackles outer joins. 

  • Self-Inflicted SQL Jul. 12, 2001
    This week, JPA looks at the "self-join," a tool that is particularly useful in certain situations, such as when you have a normalized database table that needs to be flattened. 

  • SQL Subqueries Jul. 26, 2001
    Subqueries are extremely useful in web-based database applications where you need to combine two queries and manually put them together to achieve a desired result. Subqueries allow SQL to do all of the heavy lifting! 

  • Introducing SQL Sets Aug. 2, 2001
    Because SQL is based on relational algebra, it should come as no surprise that the standard contains several set-oriented operators. In that spirit, it's time we take a look at the UNION operator. 

  • Data Definition Language Aug. 30, 2001
    GUI-based database management tools are great, but it's also important to understand the broad strokes of directly manipulating database structure. In this week's aboutSQL, JPA describes how to use SQL to define the database, its component tables, and other artifacts.  

  • Working With Tables Sep. 6, 2001
    In the last aboutSQL column, JPA introduced the Data Definition Language (DDL) and how to create database containers. This week, he moves on to creating tables and populating them with data. 

  • SQL Data Types Sep. 13, 2001
    Most database products support ANSI-SQL for manipulating data, but there is far more variance in the details of how DDL is implemented. JPA discusses data types for different SQL platforms.