『ORACLE』 PLSQL—case语句（11g）

语法：

CASE selector 

WHEN exp1 then res1

WHEN exp2 then res2

WHEN exp3 then res3

...

[ELSE resN]

end;

SQL> declare

2 mygrade char(1):='A';

3 res varchar2(20);

4 begin

5 res :=

6 CASE mygrade

7 WHEN 'A' THEN 'The mark is 90-100'

8 WHEN 'B' THEN 'The mark is 80-90'

9 WHEN 'C' THEN 'The mark is 70-80'

10 WHEN 'D' THEN 'The mark is 60-70'

11 WHEN 'E' THEN 'The mark is 0-60'

12 END;

13 dbms_output.put_line(res);

14 end;

15 /

The mark is 90-100

PL/SQL procedure successfully completed.

SQL> 2

2* mygrade char(1):='A';

SQL> ch /'A'/'F'/

2* mygrade char(1):='F';

SQL> l 

1 declare

2 mygrade char(1):='F';

3 res varchar2(20);

4 begin

5 res :=

6 CASE mygrade

7 WHEN 'A' THEN 'The mark is 90-100'

8 WHEN 'B' THEN 'The mark is 80-90'

9 WHEN 'C' THEN 'The mark is 70-80'

10 WHEN 'D' THEN 'The mark is 60-70'

11 WHEN 'E' THEN 'The mark is 0-60'

12 END;

13 dbms_output.put_line(res);

14* end;

SQL> /

PL/SQL procedure successfully completed.

SQL> declare

2 mygrade char(1):='F';

3 res varchar2(20);

4 begin

5 res :=

6 CASE mygrade

7 WHEN 'A' THEN 'The mark is 90-100'

8 WHEN 'B' THEN 'The mark is 80-90'

9 WHEN 'C' THEN 'The mark is 70-80'

10 WHEN 'D' THEN 'The mark is 60-70'

11 WHEN 'E' THEN 'The mark is 0-60'

12 ELSE 'The mark is null'

13 END;

14 dbms_output.put_line(res);

15 end;

16 /

The mark is null

PL/SQL procedure successfully completed.