Dealing with Errors

When an error occurs in a stored program, the default behavior of MySQL is to terminate execution of the program and pass the error out to the calling program. If you need a different kind of response to an error, you create an error handler that defines the way in which the stored program should respond to one or more error conditions.

The following are two relatively common scenarios that call for the definition of error handlers:

  • If you think that an embedded SQL statement might return no rows, or you need to fetch all the rows from a SELECT statement using a cursor, a NOT FOUND error handler will prevent the stored program from terminating prematurely.
  • If you think that a SQL statement might return an error (a constraint violation, for instance), you may need to create a handler to prevent program termination. The handler will, instead, allow you to process the error and continue program execution.

Chapter 6 describes in detail how to use error handlers. An example of using a NOT FOUND error handler with a cursor is shown in the next section.

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



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

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