编写SQL插入函数

Question

我正在尝试创建SQL函数,它将向表中添加条目.在添加新用户之前,我想检查一下,或者此用户已经不在表中.我写了一些代码,但由于我收到错误而无法保存:在函数内无效使用副作用opreator'INSERT'.函数中包含的最后一个语句必须是return语句.

CREATE FUNCTION [dbo].[CreateUser]
    (
    @Username varchar(20),
    @Password varchar(20),
    @Email varchar(50),
    @PasswordQuestion varchar(30),
    @PasswordAnswer varchar(30)

    )
RETURNS bit/* datatype */
AS
    BEGIN
        if  (Exists(Select Username from Users where Username=@Username and Password=@Password))
            return 1;
        else
            begin
                INSERT INTO dbo.Users (Username, Password, 
                                       Email, UserId, 
                                       IsApproved, IsLockedOut, 
                                       IsOnline, CreationDate, 
                                       PasswordQuestion, PasswordAnswer) VALUES (@Username, @Password, @Email, 
                                                                                 1, 0, 0, 0, GetDate(), 
                                                                                 @PasswordQuestion, @PasswordAnswer);
                return 0;
            end

    END

我只是初学SQL,所以任何建议都会很棒!

Answer 1

简而言之,不允许函数对任何SQL Server对象进行任何更改.存储过程可以.通过微小的更改,您的代码现在是SP.

CREATE PROC [dbo].[CreateUser]
    (
    @Username varchar(20),
    @Password varchar(20),
    @Email varchar(50),
    @PasswordQuestion varchar(30),
    @PasswordAnswer varchar(30)

    )
--RETURNS bit/* datatype */
AS
    BEGIN
        if  (Exists(Select Username from Users where Username=@Username and Password=@Password))
            return 1;
        else
            begin
                INSERT INTO dbo.Users (Username, Password, 
                                       Email, UserId, 
                                       IsApproved, IsLockedOut, 
                                       IsOnline, CreationDate, 
                                       PasswordQuestion, PasswordAnswer) VALUES (@Username, @Password, @Email, 
                                                                                 1, 0, 0, 0, GetDate(), 
                                                                                 @PasswordQuestion, @PasswordAnswer);
                return 0;
            end

    END
GO

你可以这样称呼它:

exec dbo.CreateUser 'Jim', 'Teddy', 'jim@do.not.email', 'Where', 'Here';