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C#连接MySql数据库

本机安装了mysql数据库！
C#连接mysql主要是使用了与数据库相关的动态链接库MySql.Data.dll进行操作，其中经常使用的类：

MySqlConnection: 连接MySQL服务器数据库。
MySqlCommand:执行一条sql语句。
MySqlDataReader: 包含sql语句执行的结果，并提供一个方法从结果中阅读一行。

连接数据库

private void btn(object sender, RoutedEventArgs e)
{
    string connect = "server=localhost;database=book;uid=root;pwd=123456";
    MySqlConnection conn = new MySqlConnection(connect);
    try
    {
        conn.Open();
        MessageBox.Show("连接成功！");
    }
    catch (Exception ex)
    {
        MessageBox.Show("连接失败！");
        throw;
    }
}

运行结果

查询

查询条件固定

#region 查-查询条件固定
string sql = "select * from book";
MySqlCommand cmd = new MySqlCommand(sql, conn);
MySqlDataReader reader = cmd.ExecuteReader();   //执行executeReader()返回一个MySqlReader对象
string str = "";
while (reader.Read())
{
    str += reader.GetInt32("id") + "===" + reader.GetString("name") + "===" + reader.GetString("writer") + "\n";
}
MessageBox.Show(str);
#endregion

查询条件不固定

#region 查-查询条件不固定
string sql = "select * from book where writer='籽月'";
MySqlCommand cmd = new MySqlCommand(sql, conn);
MySqlDataReader reader = cmd.ExecuteReader();   //执行executeReader()返回一个MySqlReader对象
string str = "";
while (reader.Read())
{
    str += reader.GetInt32("id") + "===" + reader.GetString("name") + "===" + reader.GetString("writer") + "\n";
}
MessageBox.Show(str);
#endregion

查询返回一个值

string sql = "select count(*) from book";
MySqlCommand cmd = new MySqlCommand(sql, conn);
object result = cmd.ExecuteScalar();//执行查询，并返回查询结果集中的第一行的第一列，所有其他的行和列将被忽略，select语句无记录返回时，executeScalar()返回null值
if (result != null)
{
    int count = int.Parse(result.ToString());
    MessageBox.Show(count.ToString());
}

增删改

#region 增
//string sql = "insert into book(id,name,price,count,writer) values('5','深入浅出WPF','33','2','刘铁猛')";
//MySqlCommand cmd = new MySqlCommand(sql, conn);
//int result = cmd.ExecuteNonQuery();
//if (result == 1)
//{
//    MessageBox.Show("添加成功！");
//}
#endregion
#region 删
//string sql = "delete from book where id=5";
//MySqlCommand cmd = new MySqlCommand(sql, conn);
//int result = cmd.ExecuteNonQuery();
//if (result == 1)
//{
//    MessageBox.Show("删除成功！");
//}
#endregion
#region 改
//string sql = "update  book set price=99 where writer='刘铁猛'";
//MySqlCommand cmd = new MySqlCommand(sql, conn);
//int result = cmd.ExecuteNonQuery();
//if (result == 1)
//{
//    MessageBox.Show("修改成功！");
//}
#endregion