Embedding generic sql queries into c# program
- by Pooja Balkundi
Okay referring to my first question code in the main, I want the user to enter employee name at runtime and then i take this name which user has entered and compare it with the e_name of my emp table , if it exists i want to display all information of that employee , how can I achieve this ?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
namespace ConnectCsharppToMySQL
{
public class DBConnect
{
private MySqlConnection connection;
private string server;
private string database;
private string uid;
private string password;
string name;
//Constructor
public DBConnect()
{
Initialize();
}
//Initialize values
private void Initialize()
{
server = "localhost";
database = "test";
uid = "root";
password = "";
string connectionString;
connectionString = "SERVER=" + server + ";" + "DATABASE=" +
database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";
connection = new MySqlConnection(connectionString);
}
//open connection to database
private bool OpenConnection()
{
try
{
connection.Open();
return true;
}
catch (MySqlException ex)
{
//When handling errors, you can your application's response based
//on the error number.
//The two most common error numbers when connecting are as follows:
//0: Cannot connect to server.
//1045: Invalid user name and/or password.
switch (ex.Number)
{
case 0:
MessageBox.Show("Cannot connect to server. Contact administrator");
break;
case 1045:
MessageBox.Show("Invalid username/password, please try again");
break;
}
return false;
}
}
//Close connection
private bool CloseConnection()
{
try
{
connection.Close();
return true;
}
catch (MySqlException ex)
{
MessageBox.Show(ex.Message);
return false;
}
}
//Insert statement
public void Insert()
{
string query = "INSERT INTO emp (e_name, age) VALUES('Pooja R', '21')";
//open connection
if (this.OpenConnection() == true)
{
//create command and assign the query and connection from the constructor
MySqlCommand cmd = new MySqlCommand(query, connection);
//Execute command
cmd.ExecuteNonQuery();
//close connection
this.CloseConnection();
}
}
//Update statement
public void Update()
{
string query = "UPDATE emp SET e_name='Peachy', age='22' WHERE e_name='Pooja R'";
//Open connection
if (this.OpenConnection() == true)
{
//create mysql command
MySqlCommand cmd = new MySqlCommand();
//Assign the query using CommandText
cmd.CommandText = query;
//Assign the connection using Connection
cmd.Connection = connection;
//Execute query
cmd.ExecuteNonQuery();
//close connection
this.CloseConnection();
}
}
//Select statement
public List<string>[] Select()
{
string query = "SELECT * FROM emp where e_name=(/*I WANT USER ENTERED NAME TO GET INSERTED HERE*/)";
//Create a list to store the result
List<string>[] list = new List<string>[3];
list[0] = new List<string>();
list[1] = new List<string>();
list[2] = new List<string>();
//Open connection
if (this.OpenConnection() == true)
{
//Create Command
MySqlCommand cmd = new MySqlCommand(query, connection);
//Create a data reader and Execute the command
MySqlDataReader dataReader = cmd.ExecuteReader();
//Read the data and store them in the list
while (dataReader.Read())
{
list[0].Add(dataReader["e_id"] + "");
list[1].Add(dataReader["e_name"] + "");
list[2].Add(dataReader["age"] + "");
}
//close Data Reader
dataReader.Close();
//close Connection
this.CloseConnection();
//return list to be displayed
return list;
}
else
{
return list;
}
}
public static void Main(String[] args)
{
DBConnect db1 = new DBConnect();
Console.WriteLine("Initializing");
db1.Initialize();
Console.WriteLine("Search :");
Console.WriteLine("Enter the employee name");
db1.name = Console.ReadLine();
db1.Select();
Console.ReadLine();
}
}
}
