General functions of NVL, NVL2, NULLIF, and COALESCE in Oracle

Java code
1. NVL Function
The NVL function format is as follows: NVL (expr1, expr2)
If the first oracle parameter is null, the value of the second parameter is displayed. If the value of the first parameter is not empty, the original value of the first parameter is displayed.
2. NVL2 Functions
The format of the NVL2 function is as follows: NVL2 (expr1, expr2, expr3)
If the first parameter of the function is null, the value of the third parameter is displayed. If the value of the first parameter is not empty, the value of the second parameter is displayed.
3. NULLIF Function
NULLIF (exp1, expr2)
The function returns NULL if exp1 and exp2 are equal. Otherwise, the first value is returned.
4. Coalesce Function
Coalesce (expr1, expr2, expr3 ..... Exprn)
One statement is to display the first parameter that is not null. If all values are null, null is returned.