Handlers

DECLARE handler_action HANDLER 
FOR condition_value
statement

Before variable or condition declarations
Actions
- What happens when the handler is called
- CONTINUE : execution continues
- EXIT : exits from the current BEGIN ... END block
- UNDO: not supported in mysql
Conditions
- mysql error code
  - These are mysql specific
  - Don't use 0 - this is success
  - See this list
- SQLSTATE value
  - SQLSTATE value (a 5-character string literal)
  - Taken from an ANSI SQL standard, so more uniform
  - Don't use 00xxx as this is a success as well.
  - In the same table as above.
- NOT FOUND
  - Shorthand for SQLSTATE starting with 02
  - (error 1329 No data - zero rows fetched, selected, or processed)
- SQLWARNING
  - SQLSTATE starting with 01
- SQLEXCEPTION
  - SQLSTATE values that do not begin with '00', '01', or '02'
- condition_name
  - We MAY learn how to declare conditions later.
If no handler is declared,
- EXCEPTION: is an exit handler
- SQLWARNING and NOT FOUND are CONTINUE handlers

Ignoring warnings:

DECLARE CONTINUE HANDLER FOR SQLWARNING BEGIN END;