Handling SQL Errors: A Preview

Handling SQL Errors A Preview

Error handling in MySQL stored programs is such an important and complex topic that we have dedicated an entire chapterChapter 6to this topic. However, let's provide a quick summary here.

By default, if a SQL statement within a stored program generates an error, the stored program will cease execution and the error will be returned to the calling program. If you don't want this to happen, you must specify an error handler using the following syntax:

 DECLARE {CONTINUE | EXIT} HANDLER FOR
 {SQLSTATE sqlstate_code| MySQL error code| condition_name}
 stored_program_statement

The handler nominates an error conditionusing a MySQL error code, an ANSI-standard SQLSTATE, or a named conditionand describes what is to happen if the error is encountered. The handler can do one of two things:

  • Allow execution to CONTINUE.
  • Immediately exit the block or stored program containing the handler.

The handler specifies stored program statements that will be executed when the handler is activated. These statements often set a status variable that could be checked within the main line of the program but that could also specify a BEGIN-END block containing many lines of code.

We have already looked at the use of handlers in determining when a cursor has returned the last row of its result set (see "Fetching an Entire Result Set" earlier in this chapter).

We discuss handlers in depth in the next chapter.

Part I: Stored Programming Fundamentals

Introduction to MySQL Stored Programs

MySQL Stored Programming Tutorial

Language Fundamentals

Blocks, Conditional Statements, and Iterative Programming

Using SQL in Stored Programming

Error Handling

Part II: Stored Program Construction

Creating and Maintaining Stored Programs

Transaction Management

MySQL Built-in Functions

Stored Functions

Triggers

Part III: Using MySQL Stored Programs in Applications

Using MySQL Stored Programs in Applications

Using MySQL Stored Programs with PHP

Using MySQL Stored Programs with Java

Using MySQL Stored Programs with Perl

Using MySQL Stored Programs with Python

Using MySQL Stored Programs with .NET

Part IV: Optimizing Stored Programs

Stored Program Security

Tuning Stored Programs and Their SQL

Basic SQL Tuning

Advanced SQL Tuning

Optimizing Stored Program Code

Best Practices in MySQL Stored Program Development

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MySQL Stored Procedure Programming
MySQL Stored Procedure Programming
ISBN: 0596100892
EAN: 2147483647
Year: 2004
Pages: 208
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