Oracle repeated field setting to null Function

The repeated fields are set to null. in oracle, we use the lag Function for analysis. If you need it, please refer to it.

Use the LAG Analysis FunctionThe repeated fields are set to null.Example:

The data in the test table TEST_XX is as follows:

To achieve the following output:

The test SQL statement is

The Code is as follows:	Copy code
SELECT CASE WHEN PRE_NAME IS NULL THEN USER_NAME ELSE NULL End as USER_NAME, COURSE, GRADE FROM (select .*, LAG (USER_NAME) OVER (partition by USER_NAME order by course) AS PRE_NAME FROM TEST_XX)