Toad World® Forums

Optimized Notations


#1

There are some notations that get appended to a join condition after running the optimizer on a query. one is “+ 0” and the other is “|| ’ '”. I assume the former is for conducting a mathematical operation. But why append a space to the end of a join condition?


#2

Hello Gerald,

The purpose of adding the +0 to a number field or the +’’ to a character field is to disable an index on that field. This result is either a full table scan or the use of a different index.

SELECT * FROM A
WHERE SALARY + 0 = ‘10000’

SELECT * FROM A
WHERE EMP_SEX || ‘’ = ‘m’