MySQL provides a sizeable library of functions to format and combine data within SQL queries in order to produce the desired results in the desired format. This appendix provides a reference to the most useful of these functions, as implemented in MySQL as of version 3.23.54a, current as of this writing.
For a complete, up-to-date reference to supported SQL functions, see the MySQL Reference Manual.
|
This function returns expr1 unless it is NULL, in which case it returns expr2. |
||
|
This function returns expr1 unless it equals expr2, in which case it returns NULL. |
||
|
If expr1 is TRUE (that is, not NULL or 0), returns expr2; otherwise, returns expr3. |
||
|
CASE value WHEN [compare-value1] THEN result1 |
This function returns result1 when value=compare-value1 (note that several compare-value/result pairs can be defined); otherwise, returns else-result, or NULL if none is defined. |
|
|
CASE WHEN [condition1] THEN result1 [WHEN ...] [ELSE |
This function returns result1 when condition is TRUE (note that several condition/result pairs can be defined); otherwise, returns else-result, or NULL if none is defined. |