c# - 如何在C#中一次性执行两个查询？

Question

我在 C# 中执行两个查询时遇到问题。当我尝试执行第二个时，它会给出以下消息:

Column 'FIRST_NAME' cannot be null

...这是指我之前成功执行的第一个查询。我认为第二个查询中仍然包含此列名称，即使我在这里没有使用它。

如您所见，我创建了一个新的 StringBuilder 对象并清除了第二个查询的参数，但不知何故我仍然收到此消息。

        // Executed first query. Now moving onto second query without calling .Close()

        // Store the last inserted id as the child's local id
        child.ID = cmd.LastInsertedId;

        // Store the child id into the parent record
        query = new StringBuilder();
        cmd.Parameters.Clear(); 

        query.Append("UPDATE players SET child_id = @child_id WHERE player_id = @player_id;");

        cmd.Parameters.AddWithValue("child_id", child.ID);
        cmd.Parameters.AddWithValue("player_id", child.ParentID);

        // Execute query
        rows_affected = cmd.ExecuteNonQuery();

        conn.Close();

Answer 1

您似乎没有为新查询设置 CommandText 属性。您仍在使用第二个查询的参数执行第一个查询。

    // Executed first query. Now moving onto second query without calling .Close()

    // Store the last inserted id as the child's local id
    child.ID = cmd.LastInsertedId;

    // Store the child id into the parent record
    query = new StringBuilder();
    cmd.Parameters.Clear(); 

    query.Append("UPDATE players SET child_id = @child_id WHERE player_id = @player_id;");

    //*** ADD THIS LINE HERE ***//
    cmd.CommandText = query.ToString();

    cmd.Parameters.AddWithValue("child_id", child.ID);
    cmd.Parameters.AddWithValue("player_id", child.ParentID);

    // Execute query
    rows_affected = cmd.ExecuteNonQuery();

    conn.Close();