FreeTDS Development Group

[Don Burden <donb AT zirmed.com>]

Ok, here's some comparisons:

TEST table:
row   id
====  ====
1               
2       1
3       12      
4       123
5       12
6       1
7

First, code running on Win2000, compiled with .NET C++, accessing SQL2000:
...
#define MAXLEN 50
SQLCHAR sID[51]
...
   SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
   SQLExecDirect(hstmt,
            (unsigned char *) "Select id from test",
            SQL_NTS);
   SQLBindCol(hstmt, 1, SQL_C_CHAR, sID, MAXLEN, &cbzName);
   while (SQLFetch(hstmt)!= SQL_NO_DATA ))
      printf("//%s//\n", sID);
...

id field was rtrimmed when changing types.

Run with id defined as char(20).  Notice padding to 20 chars, not 50.
//                    //
//1                   //
//12                  //
//123                 //
//12                  //
//1                   //
//                    //

Run with id defined as varchar(20)
////
//1//
//12//
//123//
//12//
//1//
////

Run with id defined as text
////
//1//
//12//
//123//
//12//
//1//
////

Outputs garbage data if length changed from MAXLEN to 0 or -1.
Returncode=-1 from SQLBindCol if length set to -1.  
 
====================================================

Next, same code running on Linux, FreeTDS + unixODBC

Run with id defined as char(20) (notice output is 50 chars, not 20)
//                                                  //
//1                                                 //
//12                                                //
//123                                               //
//12                                                //
//1                                                 //
//                                                  //

Run with id defined as varchar(20)  (Bad last row!)
////
//1                                                 //
//12                                                //
//123                                               //
//12                                                //
//1                                                 //
//1                                                 //

Run with id defined as text
////
//1&//
//12//
//123@//
//123@//
//123@//
//123@//

Changing length to -1 appears to be the only way to get a non-blank filled,
null terminated string when field defined as varchar(20).  (Bad last row
again!):
////
//1//
//12//
//123//
//12//
//1//
//1//