When using case in Oracle

 Case... whenConditional Conversion Functions CaseWhen there are two forms of expression1  CaseVariable whenValue 1 ThenResults 1 whenValue 2 ThenResults 2Else 'other' End --else you can choose not toExample:SelectEname,job, ( CaseJob when 'MANAGER'  ThenJob when 'Clerk'    ThenJobEnd)              fromEMP; 2  Case  whenExpression 1 ThenResults 1 whenExpression 2 ThenResults 2Else 'other' EndExample:SelectEname,sal, Case  whenDeptno=Ten  Then 'Accounting Department'                          whenDeptno= -  Then 'Research Department'                         whenDeptno= -  Then 'Sales Department'             Else 'other Departments' End               fromEMP;--after the current face condition is filtered in case, it is then extracted from the rest of the previous data. --take the EMP table below the Scott user as an example. --The order of the second method needs to be taken into account. Sql> SelectT.*, Case  whenT.sal>= the  Then '['  2                   whenT.sal< the  andT.sal>=2500  Then '[2500-3000'  3                   whenT.sal<2500  andT.sal>= the  Then '[1500-2500'  4                  Else '<1500' End  asSal_level5, Case  whenT.sal>= the  Then '['  6                   whenT.sal>=2500  Then '[2500-3000'  7                   whenT.sal>= the  Then '[1500-2500'  8                  Else '<1500' End  assal_level_test9     fromEMP T; EMPNO ename JOB MGR hiredate SAL COMM DEPTNO sal_level sal_level_test----- ---------- --------- ----- ----------- --------- --------- ------ ---------- -------------- 7369SMITH Clerk7902 1980/ A/ -     800.00                - < the      < the 7499ALLEN salesman7698 1981/2/ -     1600.00    300.00      - [1500-2500 [1500-2500 7521 WARD salesman 7698 1981/2/22 1250.00 500.00-<1500 <1500 7566 JO NES MANAGER 7839 1981/4/2 2975.00 [2500-3000 [2500-3000 7654 MARTIN salesman 7698 1981               /9/28 1250.00 1400.00 <1500 <1500 7698 BLAKE MANAGER 7839 1981/5/1 2850.00 [2500-3000 [2500-3000 7782 CLARK MANAGER 7839 1981/6/9 2450.00 10 [1500-2500 [1500-2500] 7788 SCOTT ANALYST 7566 1987/4/19 3000.00 [[7839] KING President 19     81/11/17 5000.00 [7844 TURNER salesman 7698 1981/9/8 1500.00 0.00 [1500-2500 [1500-2500 7876 ADAMS clerk 7788 1987/5/23 1100.00 <1500 <1500 790  0 JAMES Clerk 7698 1981/12/3 950.00 <1500 <1500 7902 FORD ANALYST 7566  1981/12/3 on 3000.00             [7934 MILLER clerk 7782 1982/1/23 1300.00 <1500 < 1500

When using case in Oracle