Oracle PL/SQL:IF语句的使用
作者:admin 日期:2010-05-23
原文:http://psoug.org/reference/control_struct.html
IF语句的使用
A.基本的IF条件语句：
基本语法:
IF THEN
Example:
SQL> set serveroutput on;
SQL> declare
x number(3):=9;
begin
if x<10 then
dbms_output.put_line('x is less than10');
end if;
end;
/
结果：
x is less than10
PL/SQL procedure successfully completed
B.IF - ELSE 语句
基本语法：
IF THEN
Example:
DECLARE
x NUMBER(3) := 10;
BEGIN
IF x < 10 THEN
dbms_output.put_line('X is less than 10');
ELSE
dbms_output.put_line('X is not less than 10');
END IF;
END;
/
结果：
X is not less than 10
PL/SQL procedure successfully completed
C:IF - ELSIF - ELSE 语句
基本语法:
IF THEN
Example:
set serveroutput on
DECLARE
x NUMBER(3) := 47;
BEGIN
IF x < 10 THEN
dbms_output.put_line('X is less than 10');
ELSIF x = 10 THEN
dbms_output.put_line('X is equal to 10');
ELSIF x < 100 THEN
dbms_output.put_line('X is between 11 and 99');
ELSE
dbms_output.put_line('X is greater than 99');
END IF;
END;
/
结果：
X is between 11 and 99
PL/SQL procedure successfully completed
D:与NULL值比较处理
Example:
declare
v NUMBER;
begin
if v = 1 then
DBMS_OUTPUT.put_line('Equal to 1');
elsif v!= 1 then
DBMS_OUTPUT.put_line('Not equal to 1');
elsif v = v then
DBMS_OUTPUT.put_line('Equal to itself');
else
DBMS_OUTPUT.put_line('Undefined result');
end if;
v:=v+1;
DBMS_OUTPUT.put_line('New value: <'||v||'>');
end;
/
结果:
Undefined result
New value: <>
PL/SQL procedure successfully completed
IF语句的使用
A.基本的IF条件语句：
基本语法:
复制内容到剪贴板
程序代码
程序代码IF
END IF;
Example:
复制内容到剪贴板 程序代码
程序代码SQL> set serveroutput on;
SQL> declare
x number(3):=9;
begin
if x<10 then
dbms_output.put_line('x is less than10');
end if;
end;
/
结果：
x is less than10
PL/SQL procedure successfully completed
B.IF - ELSE 语句
基本语法：
复制内容到剪贴板 程序代码
程序代码IF
ELSE
END IF;
Example:
复制内容到剪贴板 程序代码
程序代码DECLARE
x NUMBER(3) := 10;
BEGIN
IF x < 10 THEN
dbms_output.put_line('X is less than 10');
ELSE
dbms_output.put_line('X is not less than 10');
END IF;
END;
/
结果：
X is not less than 10
PL/SQL procedure successfully completed
C:IF - ELSIF - ELSE 语句
基本语法:
复制内容到剪贴板 程序代码
程序代码IF
ELSIF THEN
ELSIF THEN
ELSE
END IF;
Example:
复制内容到剪贴板 程序代码
程序代码set serveroutput on
DECLARE
x NUMBER(3) := 47;
BEGIN
IF x < 10 THEN
dbms_output.put_line('X is less than 10');
ELSIF x = 10 THEN
dbms_output.put_line('X is equal to 10');
ELSIF x < 100 THEN
dbms_output.put_line('X is between 11 and 99');
ELSE
dbms_output.put_line('X is greater than 99');
END IF;
END;
/
结果：
X is between 11 and 99
PL/SQL procedure successfully completed
D:与NULL值比较处理
Example:
复制内容到剪贴板 程序代码
程序代码declare
v NUMBER;
begin
if v = 1 then
DBMS_OUTPUT.put_line('Equal to 1');
elsif v!= 1 then
DBMS_OUTPUT.put_line('Not equal to 1');
elsif v = v then
DBMS_OUTPUT.put_line('Equal to itself');
else
DBMS_OUTPUT.put_line('Undefined result');
end if;
v:=v+1;
DBMS_OUTPUT.put_line('New value: <'||v||'>');
end;
/
结果:
Undefined result
New value: <>
PL/SQL procedure successfully completed
[本日志由 admin 于 2010-05-23 09:05 PM 编辑]
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