c# - 在父表中插入值时自动在子表中生成id

Question

我有两个表，分别是父表和子表。现在我向父表插入一个值，自动递增 id。代码是这样的:

string query2 = "INSERT INTO printer_info(printer_ip) VALUES(@ipAddress)";
MySqlCommand cmd1 = new MySqlCommand(query2, connection);

cmd1.Parameters.AddWithValue("@ipAddress", pAddress);
cmd1.ExecuteNonQuery();

现在我的问题是，当值插入到父表中时。如果想让child表中的id自动生成怎么办？请指教。

   ID | printer_ip               printer_id | page_count
   ---------------    ------>    -----------------------
    1 | 10.0.0.0                            |

   PRIMARY KEY ID                FOREIGN KEY printer_id

Answer 1

如果你也想在子行中插入一行，就在父行创建之后，那么你可以在下一个插入语句中使用 last_insert_id()。

示例:

string query2 = "INSERT INTO printer_info(printer_ip) VALUES(@ipAddress)";
MySqlCommand cmd1 = new MySqlCommand(query2, connection);

cmd1.Parameters.AddWithValue("@ipAddress", pAddress);
cmd1.ExecuteNonQuery();

string query_for_child_row = "INSERT INTO printer_queue(printer_id, page_count) 
                              VALUES( LAST_INSERT_ID(), @page_count )";
MySqlCommand cmd2 = new MySqlCommand( query_for_child_row, connection );

cmd2.Parameters.AddWithValue( "@page_count", page_count );
cmd2.ExecuteNonQuery();