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The Language of SQL- P36

The Language of SQL- P36:Research has shown that, being pressed for time, most readers tend to skip the introduction of any book they happen to read and then proceed immediately to the first real chapter. With that fact firmly in mind, we will only cover relatively unimportant material in the introduction, such as an explanation of what you will and will not learn by reading this book. | Looking Ahead 161 Our next chapter Stored Procedures and Parameters will relate how you can save multiple SQL statements in a procedure and make use of parameters in those procedures to add a degree of generality to your SQL commands. We ll also talk about the possibility of creating your own custom functions and explain how functions differ from stored procedures. Much like the views discussed in Chapter 13 stored procedures and custom functions are useful objects that you can create and store in your database to provide some extra polish and functionality for your systems. This page intentionally left blank CHAPTER 16 Stored Procedures and Parameters Keywords Introduced CREATE PROCEDURE BEGIN EXEC CALL ALTER PROCEDURE DROP PROCEDURE Up until now all of our data retrieval has been accomplished with a single statement. Even the set logic seen in the previous chapter was accomplished by combining multiple SELECTs into a single statement. We re now going to discuss a new scenario in which multiple statements can be saved into a single object known as a stored procedure. In broad terms there are two general reasons why you might want to use stored procedures To save multiple SQL statements in a single procedure To use parameters in conjunction with your SQL statements Stored procedures can in fact consist of a single SQL statement and contain no parameters. But the real value of stored procedures becomes evident when they contain multiple statements or parameters. The subject of stored procedures is quite complex. In this brief review of the subject we ll focus on an overview of the second stated reason that of using parameters in stored procedures. This is something that relates directly to the issue of how to best retrieve data from a database. As you ll see the ability to add .