c# - Guids 的 SQLite 参数问题

Question

我在使用参数时遇到了让 Guids 在 SQLite (0.4.8) 中匹配的问题，当我使用类似 userGuid = 'guid here' 的东西时它有效，但是 userGuid = @GuidHere 它没有。有人有什么想法吗？

创建:

CREATE TABLE Users
(
   UserGuid TEXT PRIMARY KEY NOT NULL, 
   FirstName TEXT, 
   LastName TEXT
)

示例数据:

INSERT INTO Users (UserGuid, FirstName, LastName) 
VALUES ('e7bf9773-8231-44af-8d53-e624f0433943', 'Bobby', 'Bobston')

删除语句(工作):

DELETE FROM Users WHERE UserGuid = 'e7bf9773-8231-44af-8d53-e624f0433943'

删除语句(不工作):

DELETE FROM Users WHERE UserGuid = @UserGuid

这是一个显示我的问题的 C# 程序:

using System;
using System.Data.SQLite;

namespace SQLite_Sample_App
{
    class Program
    {
        static void Main(string[] args)
        {
            Do();
            Console.Read();
        }

        static void Do()
        {
            using(SQLiteConnection MyConnection = new SQLiteConnection("Data     Source=:memory:;Version=3;New=True"))
            {
                MyConnection.Open();
                SQLiteCommand MyCommand = MyConnection.CreateCommand();
                MyCommand.CommandText = @"
                    CREATE TABLE Users
                    (
                       UserGuid TEXT PRIMARY KEY NOT NULL, 
                       FirstName TEXT, 
                       LastName TEXT
                    );

                    INSERT INTO Users (UserGuid, FirstName, LastName) 
                    VALUES ('e7bf9773-8231-44af-8d53-e624f0433943', 'Bobby', 'Bobston');
                    ";
                MyCommand.ExecuteNonQuery();

                MyCommand.CommandText = "SELECT Count(*) FROM Users WHERE UserGuid = 'e7bf9773-8231-44af-8d53-e624f0433943'";
                Console.WriteLine("Method One: {0}", MyCommand.ExecuteScalar());

                MyCommand.Parameters.AddWithValue("@UserGuid", new Guid("e7bf9773-8231-44af-8d53-e624f0433943"));
                MyCommand.CommandText = "SELECT Count(*) FROM Users WHERE UserGuid = @UserGuid";
                Console.WriteLine("Method Two: {0}", MyCommand.ExecuteScalar());                    
            }
        }
    }
}

编辑:

好吧，AddParamWithValue 似乎转换为 Guid 的 16 字节代表，所以我想我真的必须先将所有 guid 转换为字符串……有点烦人。

Answer 1

尝试将 GUID 的字符串而不是 GUID 对象传递给您的 AddWithValue 调用。

所以代替

MyCommand.Parameters.AddWithValue(
    "@UserGuid", new Guid("e7bf9773-8231-44af-8d53-e624f0433943"));

这样做:

MyCommand.Parameters.AddWithValue(
    "@UserGuid", "e7bf9773-8231-44af-8d53-e624f0433943");