SQL For Dummies®

Chapter 6. Manipulating Database Data

In This Chapter

• Dealing with data

• Retrieving the data you want from a table

• Displaying only selected information from one or more tables

• Updating the information in tables and views

• Adding a new row to a table

• Changing some or all of the data in a table row

• Deleting a table row

Chapters 3 and 4 reveal that creating a sound database structure is critical to maintaining data integrity. The stuff that you're really interested in, however, is the data itself — not its structure. You want to do four things with data: add it to tables, retrieve and display it, change it, and delete it from tables.

In principle, database manipulation is quite simple. Understanding how to add data to a table isn't difficult — you can add your data either one row at a time or in a batch. Changing, deleting, or retrieving table rows is also easy in practice. The main challenge to database manipulation is selecting the rows that you want to change, delete, or retrieve. The data that you want may reside in a database containing a large volume of data that you don't want. Fortunately, if you can specify what you want by using an SQL SELECT statement, the computer does all the searching for you. I guess that means manipulating a database with SQL is a piece of cake. Adding, changing, deleting, and retrieving are all easy! Hmmm. Perhaps that might be a slight exaggeration. At least let's start off easy, with a simple data retrieval.

Retrieving Data

The data manipulation task that users ...