问题描述
我在 PL/SQL 中有一个函数,它检查特定的 emp_id
是否存在,即:
I have a function in PL/SQL which checks if a particular emp_id
exists or not which is:
CREATE OR REPLACE FUNCTION checkEmpNo(eno numeric)
RETURN boolean IS
emp_number number;
BEGIN
SELECT emp_id INTO emp_number
FROM emp;
IF eno=emp_number
THEN
return true;
ELSE
return false;
END IF;
END checkEmpNo;
该函数编译成功,但是当我尝试将其运行为:
The function compiles successfully, but when I try to run it as:
DECLARE
exist boolean;
BEGIN
exist=checkEmpNo(1);
dbms_output.put_line(exist);
END;
它返回错误:
ORA-06550: line 5, column 1:
PLS-00306: wrong number or types of arguments in call to 'PUT_LINE'
ORA-06550: line 5, column 1:
PL/SQL: Statement ignored
3. BEGIN
4. exist:=checkEmpNo(1);
5. dbms_output.put_line(exist);
6. END;
我也试过这个:
DECLARE
exist boolean:=true;
BEGIN
if(exist=checkEmpNo(1))
then
dbms_output.put_line('true');
else
dbms_output.put_line('false');
end if;
END;
它返回错误:ORA-01422:exact fetch返回超过请求的行数
推荐答案
dbms_output.put_line
未重载以接受布尔参数.你可以做类似的事情
dbms_output.put_line
is not overloaded to accept a boolean argument. You can do something like
dbms_output.put_line( case when exist = true
then 'true'
else 'false'
end );
将布尔值转换为字符串,然后您可以将其传递给 dbms_output
.
to convert the boolean into a string that you can then pass to dbms_output
.
ORA-01422 错误是一个完全独立的问题.函数 checkEmpNo
包括 SELECT INTO
语句
The ORA-01422 error is a completely separate issue. The function checkEmpNo
includes the SELECT INTO
statement
SELECT emp_id
INTO emp_number
FROM emp;
如果查询返回除 1 行以外的任何内容,SELECT INTO
将生成错误.在这种情况下,如果 emp
表中有多行,您将收到错误消息.我的猜测是您希望您的函数执行类似
A SELECT INTO
will generate an error if the query returns anything other than 1 row. In this case, if there are multiple rows in the emp
table, you'll get an error. My guess is that you would want your function to do something like
CREATE OR REPLACE FUNCTION checkEmpNo(p_eno number)
RETURN boolean
IS
l_count number;
BEGIN
SELECT count(*)
INTO l_count
FROM emp
WHERE emp_id = p_eno;
IF( l_count = 0 )
THEN
RETURN false;
ELSE
RETURN true;
END IF;
END checkEmpNo;
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