Question

在这里度过一个完美的金发时刻，所以提前道歉......！

我想在输入记录到数据库中的新客户之前执行两个COUNT条件。以下代码检查用户名是否已被使用，如果适用，则拒绝注册。我想添加一个额外的COUNT来检查来自txtEmail的“CustomerEmail”是否已经存在于数据库中。

Answer 1

而不是计算所有用户并添加2个检查，只需执行一个包含2个条件的存在语句。

IF NOT EXISTS(select count(*) from [Customer] where CustomerUserName= @name AND CustomerEmail = @email)
BEGIN
   INSERT INTO [Customer] (CustomerFirstName,CustomerSurname,CustomerEmailAddress,CustomerAddress,CustomerAddressTown,CustomerAddressCity,CustomerAddressPostcode,CustomerContactNumber,CustomerUserName,CustomerPassword) VALUES (@FirstName, @Surname,@Email, @Address, @Town, @City, @Postcode,@ContactNumber,@Username,@Password)
END

Answer 2

我会使用存储过程来执行这样的操作......

显然，为params使用适当的数据类型

CREATE PROCEDURE usp_InsertUser
  @FirstName     VARCHAR(100) 
, @Surname       VARCHAR(100) 
, @Email         VARCHAR(100) 
, @Address       VARCHAR(100) 
, @Town          VARCHAR(100) 
, @City          VARCHAR(100) 
, @Postcode      VARCHAR(100) 
, @ContactNumber VARCHAR(100) 
, @Username      VARCHAR(100) 
, @Password      VARCHAR(100)
, @UserAdded     INT           OUTPUT 
AS
BEGIN
  SET NOCOUNT ON;

IF NOT EXISTS (SELECT * 
               FROM  [Customer] WITH (UPDLOCK)
               WHERE CustomerUserName = @Username)
    BEGIN 
       INSERT INTO [Customer] (CustomerFirstName,CustomerSurname,CustomerEmailAddress,CustomerAddress,CustomerAddressTown,CustomerAddressCity,CustomerAddressPostcode,CustomerContactNumber,CustomerUserName,CustomerPassword) 
       VALUES (@FirstName, @Surname,@Email, @Address, @Town, @City, @Postcode,@ContactNumber,@Username,@Password)

        SET @UserAdded = 1;
    END
ELSE 
    BEGIN

       SET @UserAdded = 0;
    END

END

应用程序代码看起来像......

// define connection and command, in using blocks to ensure disposal
using(SqlConnection conn = new SqlConnection(pvConnectionString ))
using(SqlCommand cmd = new SqlCommand("dbo.usp_InsertUser", conn))
{
    cmd.CommandType = CommandType.StoredProcedure;

    // set up the parameters
    cmd.Parameters.Add("@UserAdded", SqlDbType.Int).Direction = ParameterDirection.Output;

    cmd.Parameters.Add("@FirstName", SqlDbType.VarChar, 100);
    cmd.Parameters.Add("@Surname", SqlDbType.VarChar, 100);
    cmd.Parameters.Add("@Email", SqlDbType.VarChar, 100);
    // and so on.....


    // set parameter values
    cmd.Parameters["@FirstName"].Value = txtFirstName.Text;
    cmd.Parameters["@Surname"].Value = txtSurname.Text;
    cmd.Parameters["@Email"].Value = txtEmail.Text;
    // and so on.....

    // open connection and execute stored procedure
    conn.Open();
    cmd.ExecuteNonQuery();

    // read output value from @NewId
    int UserAdded = Convert.ToInt32(cmd.Parameters["@UserAdded"].Value);

    if (UserAdded == 1)
    {

        Response.Write("User already exists.");
    }

    conn.Close();


}

在数据插入

2 个答案: