This example deals with displaying databases installed on the current computer, the tables of the selected database and the data of the selected table.
For this 2 comboboxes and one datagridview has been taken in a windows application.
The queries that have been used are as follows.
- select name from sysdatabases - It displays databases installed on the current server.
- select table_name from information_schema.tables where table_type='base table' and table_catalog=@a"
It displays tables of the selected database.
The tables displayed are user-defined, but for the system defined databases, some system-defined tables are also displayed.
- To display the data of the selected tables, the appropriate query has been written.
Code of Form1.cs file
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace windowsdata
{
public partial class Form1 : Form
{
SqlConnection cn;
SqlCommand cmd;
public Form1()
{
InitializeComponent();
}
private void
Form1_Load(object sender, EventArgs e)
{
//all the databases on the server
cn = new SqlConnection("server=.;uid=sa;pwd=1234;database=master");
cmd = new SqlCommand("select name from sysdatabases", cn);
cn.Open();
SqlDataReader dr =
cmd.ExecuteReader();
while (dr.Read() == true)
{
comboBox1.Items.Add(dr[0].ToString());
}
dr.Close();
cn.Close();
}
private void
comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
//tables of the selected database
comboBox2.Text = "";
//clear the combobox of earlier data
if (comboBox2.Items.Count != 0)
{
comboBox2.Items.Clear();
}
//clear the
datagridview of earlier data
dataGridView1.DataSource = null;
string s =
comboBox1.SelectedItem.ToString();
cn = new SqlConnection("server=.;uid=sa;pwd=1234;database="+s);
cmd = new SqlCommand("select
table_name from information_schema.tables where table_type='base table' and
table_catalog=@a", cn);
cmd.Parameters.AddWithValue("@a",
s);
cn.Open();
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read() == true)
{
comboBox2.Items.Add(dr[0].ToString());
}
dr.Close();
cn.Close();
}
private void
comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
//data of the selected table
string s =
comboBox2.SelectedItem.ToString();
SqlDataAdapter da = new SqlDataAdapter("select * from" + " " + s, cn);
DataTable dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource = dt;
}
}
}
The snapshot of the application is as follows.
All the best.