我不太了解的关于Update Sql的东东

SqlCommand

using (SqlConnection conn = new  SqlConnection( " server=127.0.0.1;database=shui " + " ;uid= " + txt_uid.Text.Trim() + " ;pwd= " + txt_pwd.Text.Trim())
... {
    conn.Open();
    using(SqlCommand cmd = conn.CreateCommand())
    ...{
         cmd.CommandText = string.Format("UPDATE yhb SET zs = '{1}' WHERE zcm='{0}'",
               txt_zcm.Text, txt_zc.Text); // 此处放置你的 SQL 语句
         cmd.ExecuteNonQuery();
    }
}

SqlParameter

SqlConnection conn  =   new  SqlConnection( " server=127.0.0.1;database=shui "   +   " ;uid= "   +  txt_uid.Text.Trim()  +   " ;pwd= "   +  txt_pwd.Text.Trim());
            conn.Open();
            SqlCommand STcmd  =   new  SqlCommand(conn);
            STcmd.CommandText  =   " update yhb set zs = @txt_zs where zcm = @zcm " ;
            SqlParameter p1  =   new  SqlParameter( " @txt_zs " );
            p1.Value  =  txt_zs.Text;
            SqlParameter p2  =   new  SqlParameter( " @zcm " );
            p2.Value  =   " 100001 " ;
            STcmd.Parameters.Add(p1);
            STcmd.Parameters.Add(p2);
cmd.ExecuteNonQuery();

SqlCommand.Parameters.AddWithValue

SqlConnection conn = new  SqlConnection( " server=127.0.0.1;database=shui " + " ;uid= " + txt_uid.Text.Trim() + " ;pwd= " + txt_pwd.Text.Trim()); 
SqlCommand STcmd  =   new  SqlCommand( " update yhb set zs = @zs where zcm = '100001' " , conn);
STcmd.Parameters.AddWithValue( " @zs " ,txt_zs.Text);
conn.Open(); 
STcmd.ExecuteNonQuery();
conn.Close();

StringBuilder

StringBuilder strBuilder  =   new  StringBuilder( 2000 ); 
strBuilder.AppendFormat( " UPDATE yhb SET zs = '{1}' WHERE zcm='{0}' " , 
               txt_zcm.Text, txt_zc.Text); 
System.String strSql  =  strBuilder.toString();