SIGNALsyntax. You can use this syntax inside stored routines (including triggers) to raise an error condition which can be used to invoke specific error handling, or otherwise abort the stored routine. In addition, you can use the
SIGNALsyntax to convey information about what went wrong, which may be used by the caller to handle the error.
I have written about MySQL data entry validation procedures in the past. At the time, MySQL did not support any [Read more...]