Decode function to determine a condition greater than or equal to

The decode function can replace the results of a query, and decode actually function like an if statement.

Decode (VAR,VAR1,VALUE1,VAR2,VALUE2,VAR3,VALUE3) is equivalent to if Var=var1 then ... else if Var=var2 then ... else var=var3 then ...

But only if it is equal to the situation, if the judgment is greater than less than the case, such as if a>b, the only use of decode is not possible, you need to add the sign () function.

The function of the sign function is very simple, sign (VAR), if var>0, returns 1, if var<0, returns 1, if var=0, returns 0, you can make the following rewrite for a>b this situation:

Decode (A-B), -1, ' A<b ', 0, ' a=b ', 1, ' a>b ');

Decode function to determine a condition greater than or equal to