mysql - 优化案例陈述的最佳方法是什么？

Question

例如..我有三个 case 语句，我想将其值保存在变量中..

Select
    Case when 1 then variable='123' else
    case when 2 then variable='456' else
    case when 3 then variable='123456'
from 
table X where 
some conditions ;

Answer 1

例如试试这个

Select x.field,
    Case x.value 
    when 1 then '123'
    when 2 then '456'
    when 3 then '123456'
    ELSE '789'
    END AS variable
from 
table X where 
some conditions ;