Use Mysql Variable in Where Clause

Question

i want to write small select something like this

select t.id,func(t.name) from table t where func(t.name)>0

but i want to call function func only once

Can anybody help me?

You can create your function as DETERMINISTIC which should allow MySQL to cache the results. — andy, Sep 20 '14 at 19:07
The optimizer will eliminate common subexpressions. Just because you write a function twice does not mean it will be called twice. — gexicide, Sep 20 '14 at 19:08

score 0 · Accepted Answer · answered Sep 20 '14 at 19:06

0

Use HAVING:

SELECT t.id, func(t.name) AS f
FROM Table AS t
HAVING f > 0

answered Sep 20 '14 at 19:06

Barmar

1 Answers1