将空运算符存储在SQL数据库中时如何在SQL查询中执行空运算

Question

I have a table like this:

id  a     b    operation    c
-------------------------------
1    2    3       +          5
2    2    3       +          6
3    3    2       /          1
4    4    7       *         28
5   54    2       -         27
6    3    0       /          0

When we have to perform a simple arithmetic operation we simply use

 select a+b from table;

I have to use the operation column to check the value of a operation b is equal to c or not

Answer 1

Using "case" would help in your ... case

select a,operation,b,'=',
       CASE operation
           WHEN '+' then a+b 
           WHEN '*' then a*b 
           WHEN '-' then a-b
           WHEN '/' then if(b=0,'NAN',a/b)
           else null
       end AS c
from mytable;