Question

我正在编写的程序的一部分运行一些T-SQL代码。程序将继续循环运行，直到我停止它。当它第一次运行时没有问题。当它第二次运行时，我在尝试运行T-SQL代码时遇到错误。它表示代码创建的临时表之一已存在于数据库中。代码在尝试将记录插入临时表之前，会删除临时表。我不知道我是否在T-SQL代码中正确配置了它，或者它是否无法运行丢弃表的T-SQL代码（如果存在）。我还尝试将表格放在c＃代码中，这是我尝试的内容：

cn.Open();
string cmdText = @"BEGIN TRANSACTION; DROP TABLE IF EXISTS #temp850; COMMIT TRANSACTION;";                
SqlCommand command = new SqlCommand(cmdText, cn);
command.CommandType = CommandType.Text;
command.ExecuteNonQuery();
cn.Close();

这是我收到的错误消息：

There is already an object named '#temp850' in the database.

有人可以帮忙吗？

Answer 1

如果要在SQL中使用C＃中的事务，则可以使用以下示例。

private static void ExecuteSqlTransaction(string connectionString)
{
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        connection.Open();

        SqlCommand command = connection.CreateCommand();
        SqlTransaction transaction;

        // Start a local transaction.
        transaction = connection.BeginTransaction("SampleTransaction");

        // Must assign both transaction object and connection
        // to Command object for a pending local transaction
        command.Connection = connection;
        command.Transaction = transaction;

        try
        {
            command.CommandText =
                "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')";
            command.ExecuteNonQuery();
            command.CommandText =
                "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')";
            command.ExecuteNonQuery();

            // Attempt to commit the transaction.
            transaction.Commit();
            Console.WriteLine("Both records are written to database.");
        }
        catch (Exception ex)
        {
            Console.WriteLine("Commit Exception Type: {0}", ex.GetType());
            Console.WriteLine("  Message: {0}", ex.Message);

            // Attempt to roll back the transaction.
            try
            {
                transaction.Rollback();
            }
            catch (Exception ex2)
            {
                // This catch block will handle any errors that may have occurred
                // on the server that would cause the rollback to fail, such as
                // a closed connection.
                Console.WriteLine("Rollback Exception Type: {0}", ex2.GetType());
                Console.WriteLine("  Message: {0}", ex2.Message);
            }
        }
    }
}

Answer 2

在创建临时表之前，只需放置以下SQL语句

CountVectorizer

Answer 3

在sql上，您无法在同一查询中多次创建相同的临时表。

您可以在创建它之前每次删除＃temp85表：

更改此行：

string cmdText = @"BEGIN TRANSACTION; DROP TABLE IF EXISTS #temp850; COMMIT TRANSACTION;";

**我认为这不是删除临时表的方法

为此：

string cmdText = @"BEGIN TRANSACTION; if (OBJECT_ID('tempdb..#temp850')>0) drop table #temp850; COMMIT TRANSACTION;";

以编程方式使用c＃删除SQL Server 2016表

3 个答案: