Common functions of Oracle

1. NVL

The format of the NVL function is as follows: NVL (EXPR1,EXPR2)

The implication is that if the first parameter of Oracle EXPR1 is empty, then the value of the second parameter is expr2, and if the value of the first parameter expr1 is not NULL, the value of the first parameter is displayed.

2. Nvl2

The format of the NVL2 function is as follows: NVL2 (EXPR1,EXPR2, EXPR3)

The implication is that if the first parameter of the function Expr1 is not empty, then the value of the second argument is expr2, and if the value of the first parameter EXPR1 is null, the value of the third argument is displayed EXPR3.

3. Conversion functions

3.1 To_char () [Converts date and number types to character types]

Date converted to character type:

SelectTo_char (sysdate) s1, To_char (Sysdate,'YYYY-MM-DD') s2, To_char (Sysdate,'yyyy') S3, To_char (Sysdate,'YYYY-MM-DD Hh12:mi:ss') S4, To_char (Sysdate,'Hh24:mi:ss') S5, To_char (Sysdate,' Day') S6 fromDual

Number converted to character type:

Select Sal,to_char (sal,'$99999') N1,to_char (Sal,'$99,999 '  from EMP

3.2 to_date () [Converts a character type to a date type]

Insert  into Values (8000, to_date ('2004-10-10','yyyy-mm-dd') ));

3.3 To_number () to numeric type

Select to_number (To_char (sysdate,'hh12'from// number of hours displayed in digital

4. Connection Operator | |

Select ' Hello ' || '  World '  from dual

The output is: HelloWorld

Common functions of Oracle