删除语句不删除记录 [英] delete statement not deleting records

问题描述

任何人都知道为什么不从Student表中删除记录.当表为空并且我先运行匿名块时，它运行良好，但是随后当我再次运行它时，我会得到有关重复主键的错误，但这无关紧要，因为每次我运行该块时，它都应该从中删除所有记录桌子??我是SQL的新手，所以可以提供任何帮助.

Anyone know why its not deleting the records from the student table. When the table is empty and i first run the anonymous block it runs fine, but then when i run it again i get errors about duplicate primary keys, but this shouldn't matter as each time i run the block it should delete all records from the table?? I'm relatively new to SQL so any help is appreciated.

我应该补充一点，因为运行代码时出现dopl，所以该过程似乎工作正常.

I should add, the procedure seems to work fine as the dopl appears when i run the code.

这是我的功能:

 CREATE OR REPLACE FUNCTION DELETE_ALL_STUDENTS RETURN NUMBER AS
    BEGIN
    DELETE FROM STUDENTS;
    END;

这是我的程序:

 create or replace PROCEDURE DELETE_ALL_STUDENTS_VIASQLDEV AS
    BEGIN
    dbms_output.put_line('--------------------------------------------');
    dbms_output.put_line('Deleting all student rows');

    END;

这是我正在运行的匿名块，以查看是否起作用:

and this is the anonymous block i was running to see if it worked:

begin
DELETE_ALL_STUDENTS_VIASQLDEV;
ADD_STUDENT_VIASQLDEV(1,'Fred   Smith');
ADD_STUDENT_VIASQLDEV(2,'Sue    Davis');
ADD_STUDENT_VIASQLDEV(3,'Emma   Jones');
end;

推荐答案

我的功能不执行删除吗?"

"doesnt my function carry out the deleting?"

如果您调用它，它会，但是a，您不会.

It would if you called it, but alas you don't.

这不是SQL问题，而是逻辑问题.如果我们不洗碗，那碗就很脏.同样，如果您不调用删除记录的例程，则不会删除记录.

This is not a SQL problem, it's a logic problem. If we don't do the washing up the dishes remain dirty. Similarly if you don't call the routine which deletes the records the records are not deleted.

您需要在过程中调用该函数.不知道为什么要使它成为函数，并且无论如何它都不会编译，因为它没有RETURN子句.所以，我们也修复它.

You need to call the function in the procedure. Not sure why you've made it a function, and it won't compile anyway, because it doesn't have a RETURN clause. So, let's fix that too.

CREATE OR REPLACE FUNCTION DELETE_ALL_STUDENTS RETURN NUMBER AS
BEGIN
    DELETE FROM STUDENTS;
    return sql%rowcount; -- how many rows were deleted
END;
/

现在我们称之为:

create or replace PROCEDURE DELETE_ALL_STUDENTS_VIASQLDEV AS
    n number;  
BEGIN
    dbms_output.put_line('--------------------------------------------');
    dbms_output.put_line('Deleting all student rows');
    n := DELETE_ALL_STUDENTS;
    dbms_output.put_line('No of students deleted = '|| to_char(n));
END;

因此，当您运行匿名块时，现有学生将被删除，并用新学生替换.

So, when you run your anonymous block the existing students will be deleted and replaced with the new ones.

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