Common functions in Oracle

1. NVL (column, default) function handles NULL

Select NVL (null,3), NVL (4,3) from dual results shown as 3, 4. Because the first of the NVL is null, the result is the second value, the first one is not empty, and the result is the first value

Select SAL+NVL (comm,0) *12 some comm fields in the From dual table are null

2, NVL (column, return result 1 (column is not empty), return result 2 (listed as empty))

3,, nullif (expression 1, expression 2) function

Returns null if two expressions are equal, otherwise 1

4, Decode (column, value 1, output result 1, value 2, Output 2, ....) if the column is equal to which value, it outputs which result

5, COALESCE (expression 1, expression 2, expression 3, ..... ) function

The expression is 1 bits null, the value of expression 2 is displayed, if Expression 2 is also empty, the value of expression 3 is displayed, and so on

Common functions in Oracle