Question

这是this question的后续操作，我的存储过程是这样的：

IF EXISTS (SELECT * FROM sysobjects WHERE type = 'P' AND name = 'Check_Previous_Passwords')
BEGIN
    PRINT 'Dropping Procedure Check_Previous_Passwords'
    DROP  Procedure  Check_Previous_Passwords
END
GO

PRINT 'Creating Procedure Check_Previous_Passwords'
GO

CREATE Procedure Check_Previous_Passwords
    @ua_pk uniqueidentifier,
    @IncomingPassword varchar(25)
AS
    DECLARE @Temp VARCHAR(25)
    DECLARE @IsSamePassword bit

    SET @Temp = (SELECT TOP 1 up_Password 
                 FROM User_Passwords 
                 WHERE ua_fk = @ua_pk 
                 ORDER BY up_PasswordDate DESC)


    IF (EXISTS (SELECT 1 
                FROM User_Passwords up 
                WHERE up.ua_fk = @ua_pk
                AND @IncomingPassword = up.up_Password))
        BEGIN
            SELECT @IsSamePassword = 1

        END
    ELSE
        BEGIN
            SELECT @IsSamePassword = 0

        END
GO

GRANT EXEC ON Check_Previous_Passwords TO WEB

GO

我确定相关的SQL正在返回一个值。但是，当我将它带入我的VB.Net解决方案并使用它时，它说明我的＆＃34;表达式不会产生值＆＃34;。那么这是我的VB代码：

点击按钮：

If user_.Check_Previous_Passwords(user_) = True Then
    'throw error and set ResetPassword to true
End If

User.vb上的

Public Sub Check_Previous_Passwords(ByVal User As FoundationLibrary.User)
    Dim IsSamePassword_ As Integer
    Dim objCommand As New SqlCommand("Check_Previous_Passwords", DatabaseInterface_.Connection)
    objCommand.CommandType = CommandType.StoredProcedure
    objCommand.Parameters.AddWithValue("@ua_pk", ua_pk_)
    objCommand.Parameters.AddWithValue("@IncomingPassword", ua_Password_)
    DatabaseInterface_.Open()
    IsSamePassword_ = objCommand.ExecuteScalar
    DatabaseInterface_.Close()
    If IsSamePassword_ = 1 Then
        User.ua_ResetPassword_ = True
    Else
        User.ua_ResetPassword_ = False
    End If
End Sub

我使用了Dim IsSamePassword As Boolean，然后将If语句更改为等于True。仍然抛出相同的错误。

我有这种感觉真的很容易。

Answer 1

您的存储过程不会返回任何值。 SELECT @IsSamePassword = 0 statement only let the value 0到@IsSamePassword变量。将SELECT @IsSamePassword语句写入您的过程结尾或删除@IsSamePassword变量。

CREATE Procedure Check_Previous_Passwords
@ua_pk uniqueidentifier,
@IncomingPassword varchar(25)
AS
DECLARE @Temp VARCHAR(25)
DECLARE @IsSamePassword bit

SET @Temp = (SELECT TOP 1 up_Password 
             FROM User_Passwords 
             WHERE ua_fk = @ua_pk 
             ORDER BY up_PasswordDate DESC)


IF (EXISTS (SELECT 1 
            FROM User_Passwords up 
            WHERE up.ua_fk = @ua_pk
            AND @IncomingPassword = up.up_Password))
    BEGIN
        SELECT  1

    END
ELSE
    BEGIN
        SELECT  0

    END

或者

CREATE Procedure Check_Previous_Passwords
@ua_pk uniqueidentifier,
@IncomingPassword varchar(25)  
AS
DECLARE @Temp VARCHAR(25)
DECLARE @IsSamePassword bit

SET @Temp = (SELECT TOP 1 up_Password 
             FROM User_Passwords 
             WHERE ua_fk = @ua_pk 
             ORDER BY up_PasswordDate DESC)


IF (EXISTS (SELECT 1 
            FROM User_Passwords up 
            WHERE up.ua_fk = @ua_pk
            AND @IncomingPassword = up.up_Password))
    BEGIN
        SELECT @IsSamePassword = 1

    END
ELSE
    BEGIN
        SELECT @IsSamePassword = 0

    END

 SELECT @IsSamePassword

Answer 2

SQL比它需要的更复杂 - 你可以使用

CREATE Procedure Check_Previous_Passwords
    @ua_pk uniqueidentifier,
    @IncomingPassword varchar(25)
AS
    SELECT COUNT(*)
    FROM User_Passwords up 
    WHERE up.ua_fk = @ua_pk
        AND @IncomingPassword = up.up_Password

并且使用它的VB需要是一个函数，以便它可以返回一个值：

Option Strict On
' ...'
Public Function Check_Previous_Passwords(ByVal User As FoundationLibrary.User) As Boolean
    Dim isSamePassword As Integer
    Dim objCommand As New SqlCommand("Check_Previous_Passwords", DatabaseInterface_.Connection)
    objCommand.CommandType = CommandType.StoredProcedure
    objCommand.Parameters.Add(New SqlParameter With {.ParameterName"@ua_pk", .SqlDbType = SqlDbType.UniqueIdentifier, .Value = ua_pk_})
    objCommand.Parameters.Add(New SqlParameter With {.ParameterName = "@IncomingPassword", .SqlDbType = SqlDbType.VarChar, .Size = 25, .Value = ua_Password_})
    DatabaseInterface_.Open()
    isSamePassword = CInt(objCommand.ExecuteScalar)
    DatabaseInterface_.Close()

    User.ua_ResetPassword_ = (isSamePassword = 1)

    Return User.ua_ResetPassword_

End Function

我将AddWithValue部分更改为可靠运行的版本。你应该避免AddWithValue - 它最终只会给你带来痛苦：Can we stop using AddWithValue() already?

Answer 3

这只是为了向您展示更多功能和技巧。事实上，您可以在SP中真正使用RETURN

. . . . . 
IF EXISTS (SELECT ... )
    RETURN  1
ELSE
    RETURN  0
. . . . .

有了这个，你需要修改VB调用，最后在参数方向包含一个返回参数

p.Direction = ParameterDirection.ReturnValue

从存储过程获取返回值并在程序中使用它

3 个答案: