The first step, the namespace:
using System.Data.SqlClient;
The second step is to declare variables
public bool bConnect=false;//Database connection identification
SqlConnection con = new SqlConnection();
The third step is to connect to the database
public void ConnectSql()
{
con.ConnectionString = "server=192.168.0.110,1433;Database=db;uid=sa;pwd=sa123;";
try
{
con.Open();
}
catch (System.Exception ex)
{
string strErr = ex.ToString();
MessageBox.Show(strErr);
return;
}
MessageBox.Show("sql连接成功");
bConnect = true;
}
The fourth step, query data
if (!bConnect)
{ MessageBox.Show("Database is not connected"); return; } string strOrder="ORDER001"; if (textBox1.Text!="") { strOrder = textBox1.Text; } string str3 = "" ; string str26 = ""; string str27 = ""; string str28 = ""; //Create database command SqlCommand cmd = con.CreateCommand(); //Create query statement cmd.CommandText = "SELECT *FROM MOCTA where T002= '" + strOrder + "'"; //Read the data stream from the database and store it in the reader
SqlDataReader reader = cmd.ExecuteReader();
//Read the next line of data from the reader, if there is no data, reader.Read() returns fasle
while (reader.Read())
{ if (reader["T026"]!= System.DBNull.Value)//Judging whether the read data is empty { str26 = reader.GetString(reader.GetOrdinal("T026")); } else { MessageBox.Show("T026 is empty"); }
if (reader["T027"] != System.DBNull.Value)
{
str27 = reader.GetString(reader.GetOrdinal("T027"));
}
else
{
MessageBox.Show("T027为空");
}
if (reader["T028"] != System.DBNull.Value)
{
str28 = reader.GetString(reader.GetOrdinal("T028"));
}
else
{
MessageBox.Show("T028为空");
}
if (reader["T003"]!=System.DBNull.Value)
{
str3 = reader.GetString(reader.GetOrdinal("T003"));
}
else
{
MessageBox.Show("为空");
}
Console.WriteLine(str3 + " " + str26 + " " + str27 + " " + str28);
}
reader.Dispose();