『ORACLE』 PLSQL-case语句（11g）
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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.
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