C# 连接数据库（添加，修改，删除）

/// <summary>
/// 添加年级表
/// INSERT INTO grade VALUES('IT11')
/// </summary>
private static void addGrade(string gname)
{
SqlConnection con = null;
try
{
//1.连接字符串
string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";

//2.连接对象
con = new SqlConnection(str);

//3.打开连接
con.Open();

//4.sql语句
//INSERT INTO grade VALUES('IT11')
StringBuilder bulider = new StringBuilder();
bulider.AppendLine("INSERT");
bulider.AppendLine(" INTO ");
bulider.AppendLine(" grade ");
bulider.AppendLine(" VALUES ");
bulider.AppendFormat("('{0}') ", gname);
// Console.WriteLine(bulider.ToString());

//5.命名对象
SqlCommand cmd = new SqlCommand(bulider.ToString(), con);

//6.执行sql语句 返回Int
int count = cmd.ExecuteNonQuery();

// Console.WriteLine(count);

if (count > 0)
{
Console.WriteLine("OK!");
}
else
{
Console.WriteLine("no!");
}

}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
con.Close();
}

}

/// <summary>
/// 修改学生表
/// UPDATE stu SET BornDate='1992-1-1',Phone='80011011' WHERE StudentName='白燕'
/// </summary>
private static void updateStudent(string date,string tel,string name)
{
SqlConnection con = null;
try
{
//1.连接字符串
string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";

//2.连接对象
con = new SqlConnection(str);

//3.打开连接
con.Open();

//4.sql语句
//UPDATE stu SET BornDate='1992-1-1',Phone='80011011' WHERE StudentName='白燕'
StringBuilder bulider = new StringBuilder();
bulider.AppendLine("UPDATE");
bulider.AppendLine(" stu ");
bulider.AppendLine(" SET ");
bulider.AppendFormat("  BornDate='{0}',Phone='{1}' ",date,tel);
bulider.AppendLine(" WHERE ");
bulider.AppendFormat("StudentName='{0}' ", name);
// Console.WriteLine(bulider.ToString());

//5.命名对象
SqlCommand cmd = new SqlCommand(bulider.ToString(), con);

//6.执行sql语句 返回Int
int count = cmd.ExecuteNonQuery();

// Console.WriteLine(count);

if (count > 0)
{
Console.WriteLine("OK!");
}
else
{
Console.WriteLine("no!");
}

}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
con.Close();
}

}

/// <summary>
/// 删除学生表
/// delete stu WHERE StudentName='白燕'
/// </summary>
private static void delStudent(string name)
{
SqlConnection con = null;
try
{
//1.连接字符串
string str = "Data Source=.;Initial Catalog=MySchool;Integrated Security=True";

//2.连接对象
con = new SqlConnection(str);

//3.打开连接
con.Open();

//4.sql语句
// delete stu WHERE StudentName='白燕'
StringBuilder bulider = new StringBuilder();
bulider.AppendLine("delete");
bulider.AppendLine(" stu ");
bulider.AppendLine(" WHERE ");
bulider.AppendFormat("StudentName='{0}' ", name);
// Console.WriteLine(bulider.ToString());

//5.命名对象
SqlCommand cmd = new SqlCommand(bulider.ToString(), con);

//6.执行sql语句 返回Int
int count = cmd.ExecuteNonQuery();

// Console.WriteLine(count);

if (count > 0)
{
Console.WriteLine("OK!");
}
else
{
Console.WriteLine("no!");
}

}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
con.Close();
}

}