c# - Updating rows on a table with condition -

i'm trying delete rows, starting bottom of table using condition, when conditions met want stop updating table , leave rest was. example, if last entry on table meets it, delete it, if 1 after not meet condition stop there, , exite loop. here's code got, deleting rows :

 private void button1_click(object sender, eventargs e)     {         messagebox.show("a atualizar dados");         bool check = true;                 {             string connectionstring = @"data source=.\wintouch;initial catalog=bbl;user id=sa;password=pa$$w0rd";             string querystring = string.empty;             using (sqlconnection connection = new sqlconnection(connectionstring))             {                 connection.open();                  querystring = "delete wgcdoccab                  serie ='1' , tipodoc ='fss'                  , contribuinte ='999999990'                  , datadoc = convert(varchar(10),(dateadd(dd, -2, getdate())),120)"                  sqlcommand command = new sqlcommand(querystring, connection);                 //command.connection.open();                 command.executenonquery();              }             using (sqlconnection connection = new sqlconnection(connectionstring))             {                 connection.open();                  querystring = "select * wgcdoccab                  serie !='1' , tipodoc !='fss'                 , contribuinte !='999999990'                  ,  datadoc != convert(varchar(10),(dateadd(dd, -1, getdate())),120) ";                  using (sqlcommand command = new sqlcommand(querystring, connection))                 using (sqldatareader reader = command.executereader())                 {                     if (reader.hasrows)                     {                          check = true;                      }                     else                     {                         check = false;                         messagebox.show("dados apagados com sucesso");                     }                     command.connection.close();                 }             }         }         while (check); 

try example:

delete tablename id >  (     select max(id)     tablename     condition = false ) 

for example, if want delete until value 4:

delete tablename id >  (     select max(id)     tablename     tablename.value = 4 ) 

if table rows are:

|id|value| | 1|    7| | 2|    4| 

then subselect 2 , no rows deleted. however, if rows are:

|id|value| | 1|    7| | 2|    4| | 3|    9| | 4|    1| 

then subselect still return id of 2, , last 2 rows deleted.