oracle 在 CURSOR FOR LOOP 中使用游标属性
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using cursor attributes in a CURSOR FOR LOOP
提问by Divas
I am running the following in the Scott schema:
我在 Scott 模式中运行以下内容：
SET serveroutput ON;
BEGIN
FOR c_Emp IN (SELECT * FROM emp)
LOOP
dbms_output.put_line('The record processed by the cursor ' || c_Emp%rowcount);
END LOOP;
end;
This gives the error:
这给出了错误：
cursor attribute may not be applied to non-cursor 'C_EMP'
游标属性可能不适用于非游标“C_EMP”
However if this is done using an explicit cursor it works fine:
但是，如果这是使用显式游标完成的，则它可以正常工作：
set serveroutput on ;
设置服务器输出；
DECLARE
emp_record emp%ROWTYPE;
count_variable NUMBER;
CURSOR c IS
SELECT * FROM emp;
BEGIN
OPEN c;
loop
fetch c INTO emp_record;
exit WHEN c%notfound;
dbms_output.put_line ('The record count is ' || c%rowcount);
END loop;
close c;
end;
Just want to understand : whether while using the CURSOR FOR LOOP, is the index variable not a cursor attribute, if so why? could someone plz expalin this....
只是想了解：是否在使用 CURSOR FOR LOOP 时，索引变量不是游标属性，如果是为什么？有人可以解释一下这个....
回答by schurik
c_Empis not the cursor, its a record with felds for each column in the SELECT statment
c_Emp不是游标，它是 SELECT 语句中每一列的字段记录
c_Empis similar to the emp_recordfrom your second example.
c_Emp类似于emp_record你的第二个例子。
回答by Baljeet
Even while using a FOR loop the cursor has to be explicitly defined. A sample use of FOR loop with a cursor would look like below:
即使在使用 FOR 循环时，也必须明确定义游标。带有游标的 FOR 循环的示例使用如下所示：
declare
cursor c1 is select a from table;
begin
FOR b in c1
loop
<required logic>
end loop;
end;
回答by gary sze
To get the index in a for loop, you can add the rownumpseudocolumn in the select clause of implicit cursor.
要获取for循环中的索引，可以在隐式游标的select子句中添加rownum伪列。
SET serveroutput ON;
BEGIN
FOR c_Emp IN (SELECT e.*, rownum FROM emp e)
LOOP
dbms_output.put_line('The record processed by the cursor ' || c_Emp.rownum);
END LOOP;
end;
