csharp MySQL c＃代码

Posted 2021-05-12

 public List<string> Select(string n) {
            n = n.ToUpper();
            string query = "SELECT * FROM mydata WHERE name = '" + n + "'";

            string result = "";
            List<string> list = new List<string>();

            if (this.OpenConection()) {
                MySqlCommand cmd = new MySqlCommand(query, mySqlConnection);
                MySqlDataReader dataReader = cmd.ExecuteReader();

                while (dataReader.Read()) {
                    list.Add(dataReader.GetString("name"));
                    list.Add(dataReader.GetString("age"));
                    list.Add(dataReader.GetString("email"));
                    list.Add(dataReader.GetString("contact"));
                }

                dataReader.Close();
                this.CloseConnection();

                return list;
            }


            return list;
        }

public bool Insert(string n, int a, string e, string c ) {
            n = n.ToUpper();

            if (this.ContactExist(n)) {
                return false;
            }

            string query = "INSERT INTO mydata(name, age, email, contact) VALUES('"+n+"','"+a+"','"+e+"','"+c+"')";

            if (this.OpenConection()) {
                MySqlCommand sqlCommand = new MySqlCommand();
                sqlCommand.CommandText = query;
                sqlCommand.Connection = mySqlConnection;
                sqlCommand.ExecuteNonQuery();
                this.CloseConnection();
            }
            return true;
        }

        bool ContactExist(string n) {

            string query = "SELECT * FROM mydata WHERE name = '"+n+"'";
            string name = "";

            if (this.OpenConection())
            {
                MySqlCommand cmd = new MySqlCommand(query, mySqlConnection);
                MySqlDataReader dataReader = cmd.ExecuteReader();

                while (dataReader.Read())
                {
                    name = dataReader.GetString("name");
                }

                dataReader.Close();
                this.CloseConnection();

                if (name == n)
                {
                    return true;
                }
            }
                return false;
        }

        public void Update(string n, int a, string e, string c) {
            n = n.ToUpper();
            string query = "UPDATE mydata SET age = '"+a+"', email = '"+e+"', contact = '"+c+"' WHERE name = '"+n+"'";

            if (this.OpenConection()) {
                MySqlCommand cmd = new MySqlCommand();
                cmd.CommandText = query;
                cmd.Connection = mySqlConnection;
                cmd.ExecuteNonQuery();
                this.CloseConnection();
            }
        }

        public void Delete(string n) {
            n = n.ToUpper();
            string query = "DELETE FROM mydata WHERE name = '"+n+"'";

            if (this.OpenConection()) {
                MySqlCommand cmd = new MySqlCommand();
                cmd.CommandText = query;
                cmd.Connection = mySqlConnection;
                cmd.ExecuteNonQuery();
                this.CloseConnection();
            }
        }

        public List<string> Search(string n) {
            n = n.ToUpper();
            string query = "SELECT * FROM mydata WHERE name = '" + n + "'";

            string result = "";
            List<string> list = new List<string>();

            if (this.OpenConection()) {
                MySqlCommand cmd = new MySqlCommand(query, mySqlConnection);
                MySqlDataReader dataReader = cmd.ExecuteReader();

                while (dataReader.Read()) {
                    list.Add(dataReader.GetString("name"));
                    list.Add(dataReader.GetString("age"));
                    list.Add(dataReader.GetString("email"));
                    list.Add(dataReader.GetString("contact"));
                }

                dataReader.Close();
                this.CloseConnection();

                return list;
            }


            return list;
        }

using MySql.Data.MySqlClient;

namespace DesktopContactsManager
{
    class SqlDB
    {
        private MySqlConnection mySqlConnection;
        private string server;
        private string database;
        private string uid;
        private string pass;

        public SqlDB() {
            Initialize();
        }

        //db name = mycontacts
        //table used = mydata

        private void Initialize() {
            server = "localhost";
            uid = "sarthak";
            pass = "sarthak1997";
            database = "mycontacts";

            string connectionString;
            connectionString = "SERVER=" + server + ";" + "DATABASE=" +
            database + ";" + "UID=" + uid + ";" + "PASSWORD=" + pass + ";";

            mySqlConnection = new MySqlConnection(connectionString);
        }

        public bool OpenConection() {

            try
            {
                mySqlConnection.Open();
                return true;
            }
            catch (Exception e) {
                return false;
            }
           
        }

        public bool CloseConnection() {
            try
            {
                mySqlConnection.Close();
                return true;
            }
            catch (Exception e)
            {
                return false;
            }
        }

}