MySql Last_Insert_Id() 的并发问题... (C#) [英] Concurrency Problem With MySql Last_Insert_Id()... (C#)
问题描述
我不太确定为什么下面的控制台应用程序没有为 last_insert_id() 产生预期的行为.我读过 last_insert_id() 返回特定连接的最后一个 auto_incremented 值,但在此代码中,两个连接返回相同的结果.有人能解释一下我哪里出错了吗?
I'm not really sure why the following console application doesn't produce the expected behavior for last_insert_id(). I've read that last_insert_id() returns the last auto_incremented value for a particular connection, but in this code, the same result is returned for both connections. Can someone explain where I've gone wrong?
static void Main(string[] args)
{
string ConnectionString = "server=XXXX;database=XXXX;username=XXXX;password=XXXX;pooling=true;max pool size=100;min pool size=0";
MySqlConnection conn1 = new MySqlConnection(ConnectionString);
MySqlConnection conn2 = new MySqlConnection(ConnectionString);
MySqlCommand command1 = new MySqlCommand();
MySqlCommand command2 = new MySqlCommand();
command1.Connection = conn1;
command2.Connection = conn1;
StringBuilder createTableCommandText = new StringBuilder();
createTableCommandText.Append("Create Table TestTable (");
createTableCommandText.Append("Id INT NOT NULL AUTO_INCREMENT, ");
createTableCommandText.Append("str VARCHAR(20) NOT NULL, ");
createTableCommandText.Append("PRIMARY KEY (Id));");
StringBuilder insertCommandText = new StringBuilder();
insertCommandText.Append("INSERT INTO TestTable (str) VALUES ('what is the dilleo?');");
StringBuilder getLastInsertId = new StringBuilder();
getLastInsertId.Append("SELECT LAST_INSERT_ID();");
conn1.Open();
conn2.Open();
command1.CommandText = createTableCommandText.ToString();
command1.ExecuteNonQuery();
command1.CommandText = insertCommandText.ToString();
command2.CommandText = insertCommandText.ToString();
command1.ExecuteNonQuery();
command2.ExecuteNonQuery();
command1.CommandText = getLastInsertId.ToString();
Console.WriteLine("Command 1: {0}", command1.ExecuteScalar().ToString());
command2.CommandText = getLastInsertId.ToString();
Console.WriteLine("Command 2: {0}", command2.ExecuteScalar().ToString());
conn1.Close();
conn2.Close();
Console.ReadLine();
}
我知道这不会发生,因为顶部连接字符串中的池化,因为我尝试在没有该部分字符串的情况下运行程序,但我仍然得到相同的结果(即命令 1 和命令 2last_insert_id() 显示相同的值).欢迎任何想法!
I know that this is not happening because of the pooling in the connection string at top, since I tried running the program without that part of the string, and I still got the same results (i.e. that both Command 1 and Command 2 displayed the same value for last_insert_id()). Any ideas are welcome!
非常感谢,
安德鲁
推荐答案
看这里:
command1.Connection = conn1;
command2.Connection = conn1;
您对两个命令使用相同的连接.
You are using the same connection for both commands.
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