C# 连接操作MYSQL 数据库_02

using MySql.Data.MySqlclient; // 引进MYSQL 库 // C# 连接 MYSQL 数据库更好的方法 void func_02()
{
string str_conn_info = "";
str_conn_info += " Host = " + db_ip + ";";
str_conn_info += " Database = " + db_ip + ";";
str_conn_info += " User = " + db_ip + ";";
str_conn_info += " password = " + db_ip + ";";
str_conn_info += " port = " + db_ip + ";";
str_conn_info += " Charset = utf8"; MySqlCommand sql_cmd = new MySqlCommand();
sql_cmd.Connection = new MySqlConnection(); sql_cmd.Connection.ConnectionString = str_conn_info; if (!connect_to_mysql(sql_cmd.Connection))
{
// 连接失败
return;
} try
{
// 添加SQL 语句，并运行
sql_cmd.CommandText = "SELECT mail_id, mail_src_id, first_read_time, get_items_time, del_mail_time"
+ " FROM log_mail WHERE player_id = 1"; // 运行的结果集放到MySqlDataReader 中
MySqlDataReader data_reader = sql_cmd.ExecuteReader(); // 从结果集中取数据
try
{
while (data_reader.Read())
{
PlayerMailRecordForm.struMailRecord mail_record = new PlayerMailRecordForm.struMailRecord();
mail_record.mail_id = data_reader.GetUInt32("mail_id");
mail_record.mail_src_id = data_reader.GetUInt32("mail_src_id");
mail_record.str_first_read = data_reader.GetString("first_read_time");
if (data_reader["get_items_time"] != DBNull.Value) // 如果该字段 IS NOT NULL
mail_record.str_get_items = data_reader.GetString("get_items_time");
if (data_reader["del_mail_time"] != DBNull.Value)
mail_record.str_del_mail = data_reader.GetString("del_mail_time");
} // 关闭结果集，如果不关闭，下次运行SQL 语句时会出问题。
data_reader.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message); // 关闭结果集，如果不关闭，下次运行SQL 语句时会出问题。
data_reader.Close();
return;
}
}
catch (System.Exception ex)
{
MessageBox.Show(ex.Message);
disconnect_from_mysql(sql_cmd.Connection);
return;
} // 关闭连接
disconnect_from_mysql(sql_cmd.Connection); // 这里没有找到对于MySqlCommand 释放的方法，感觉应该是没有，不过也没关系了，这里整个对象都回收了，应该是OK的。
} public bool connect_to_mysql(MySqlConnection conn_clt)
{
switch (conn_clt.State)
{
case ConnectionState.Open:
case ConnectionState.Connecting:
case ConnectionState.Executing:
case ConnectionState.Fetching:
case ConnectionState.Broken:
break;
case ConnectionState.Closed:
default:
try
{
conn_clt.Open();
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
return false;
}
break;
} return true;
} public void disconnect_from_mysql(MySqlConnection conn_clt)
{
switch (conn_clt.State)
{
case ConnectionState.Open:
case ConnectionState.Connecting:
case ConnectionState.Executing:
case ConnectionState.Fetching:
case ConnectionState.Broken:
conn_clt.Close();
break;
case ConnectionState.Closed:
default:
break;
}
}