oracle sql语句中使用if逻辑

l在 SQL 语句中使用IF-THEN-ELSE 逻辑

l

l使用两种方法:

•CASE 表达式：SQL99的语法，类似Basic，比较繁琐

•DECODE 函数：Oracle自己的语法，类似Java，比较简介

 SQL> select ename,job, sal, case job when 'PRESIDENT' then 1.1*sal
   2                               when 'MANAGER' then 1.2*sal
   3                                when 'CLERK' then 1.3*sal
   4                                 else 1.4*sal
   5                                end 涨后薪水
   6  from emp
   7  ;

 ENAME      JOB             SAL       涨后薪水
 ---------- --------- --------- ----------
 SMITH      CLERK        800.00       1040
 ALLEN      SALESMAN    1600.00       2240
 WARD       SALESMAN    1250.00       1750
 JONES      MANAGER     2975.00       3570
 MARTIN     SALESMAN    1250.00       1750
 BLAKE      MANAGER     2850.00       3420
 CLARK      MANAGER     2450.00       2940
 KING       PRESIDENT   5000.00       5500
 TURNER     SALESMAN    1500.00       2100
 JAMES      CLERK        950.00       1235
 FORD       ANALYST     3000.00       4200
 MILLER     CLERK       1400.00       1820
 jack_1234              2000.00       2800

 13 rows selected

 SQL> select ename,job, sal,decode(job,'PRESIDENT',1.1*sal,
   2                                   'MANAGER',1.2*sal,
   3                                   'CLERK',1.3*sal,
   4                                           1.4*sal)涨后薪水
   5  from emp;

 ENAME      JOB             SAL       涨后薪水
 ---------- --------- --------- ----------
 SMITH      CLERK        800.00       1040
 ALLEN      SALESMAN    1600.00       2240
 WARD       SALESMAN    1250.00       1750
 JONES      MANAGER     2975.00       3570
 MARTIN     SALESMAN    1250.00       1750
 BLAKE      MANAGER     2850.00       3420
 CLARK      MANAGER     2450.00       2940
 KING       PRESIDENT   5000.00       5500
 TURNER     SALESMAN    1500.00       2100
 JAMES      CLERK        950.00       1235
 FORD       ANALYST     3000.00       4200
 MILLER     CLERK       1400.00       1820
 jack_1234              2000.00       2800

 13 rows selected