The following configuration is used to access MSSQL servers
 a) PDO_ODBC (PhP 5.2.6 + fixes)
 b) unixODBC (2.2.12)
 c) FreeTDS (0.82 + fixes)
 d) MS SQL Server 2005
 
Mandatory Patches
-----------------
 - PhP PDO/ODBC driver incorrectly handles long binary fields in the queries 
 (resulting in "Out of memory" error). This is a fix. Php bug #42765.
 The patch against php-5.2.6 (mandatory if BLOB data is used):
    http://dside.dyndns.org/projects/patches.dir/php-ds-odbc_blob.patch

 - unixODBC (at least up to 2.2.12) expects pointer on 32 bit interger as
 last parameter of SQLBindCol call (MSDN defines SQLLEN). However, the php
 on Linux 64 bit platform is passing 64 bit integer. This causes crash.
 Unfortunately, it is really hard work to fix it on unixODBC side (expected in 
 2.2.13). Therefore, the parts of the problem which is involving PDO/ODBC 
 misbehaviour is fixed on PhP side.
 The patch against php-5.2.6 (mandatory):
    http://dside.dyndns.org/projects/patches.dir/php-ds-odbc64.patch
 
 - FreeTDS (0.82 and earlier) ODBC driver is corrupting data if SQLGetData is 
 called multiple times on a single column and  BINARY->CHAR data conversion 
 has been involved. 
 The patch agains FreeTDS-0.82 (mandatory if BLOB data bigger than 512 bytes
 is used):
    http://dside.dyndns.org/projects/patches.dir/freetds-0.82-odbc-csa2.patch 
 
Optional Patches
----------------
 - PhP (5.2.6 and earlier) PDO/ODBC driver is ignoring PDO::ATTR_TIMEOUT 
 attribute, what causes extremly long delays trying to access dead / unreachable
 servers. Php bug #45287. 
 The patch agains php-5.2.6 (optional, recommended):
    http://dside.dyndns.org/projects/patches.dir/php-ds-odbc_timeout.patch

 - FreeTDS uses SQL_ATTR_CONNECTION_TIMEOUT instead SQL_ATTR_LOGIN_TIMEOUT
 on connection initialization. This do not causing big problems, but
 violites ODBC specification.
 The patch against php-5.2.6 (optional):
 http://dside.dyndns.org/projects/patches.dir/freetds-ds-connect_timeout.patch

 - Be aware what PDO/ODBC returns BINARY blobs converted to ASCII hexdecimal 
 representation. I decieded against patching this behaviour in driver code, 
 but just taking care in php code.
 However, to insert data in the binary blob, it is neccesary to provide the 
 data in binary form. 

Known problems
--------------
 - PhP (5.2.6) PDO/ODBC driver incorrectly handles PDO::PARAM_LOB parameters if 
 $length attribute is set. No fix is available upto now, just avoid setting the
 $length attribute.

 - Either PDO/ODBC module or FreeTDS is sending all the data (with exception of
 PDO::PARAM_LOB) to MSSQL server using TEXT variables. However, MSSQL is not 
 able to make implicit conversion of TEXT variables. 
 This causes troubles while writing INSERT queries. The problem could be 
 avoided by making explicit conversion to size-limit CHAR type in INSERT 
 query. Like this:
    INSERT INTO ... (intcol) VALUE(CONVERT(CHAR(64), ?));
    
 - after 'prepare' call, the query (at least INSERT one) could be 'execute' 
 only 65535 times. Afterwars, strange excpetion is emerges. Just repraparing
 is not helpful. It's necessary to close PDO connection and open it again.

Reciptes
-------- 
 - Inserting the datetime values into MSSQL database is quite tricky, I'm
 using following procedure:
  * Setting date format:
    $dbh->query("set dateformat ymd");
  * Formating date string:
    $sqltime = strftime("%Y-%m-%d %H:%M:%S", floor($tm));
  * Preparing SQL query:
    ... VALUES( ... CONVERT(DATETIME, CONVERT(CHAR(20), ?), 111) ... ) ...


More Infos
----------
 - FreeTDS ODBC driver is not implementing SQLDescribeType interface. Therefore,
 php is not able to detect sql_type for SQL_BIND_PARAM call. It tries to guess:
    LOB columns 	- the VAR_BINARY is guessed
    everything else	- the VAR_CHAR is guessed

 Therefore, the wrong sql_type will be guessed if we have a BINARY column, but 
 not using LOB parameter.
 
 This causes INSERT calls to fail. Therefore, it is mandatory necessary to 
 specify LOB type for all INSERTs on binary blobs. The SELECTs are not affected.

 - To change behaviour of PhP PDO/ODBC driver which is returning binary blobs
 in ASCII hexdecimal representation, it is neccessary to alter SQL_C_CHAR
 data type currently passed to the SQLGetData within following function:
	    odbc_stmt.c/odbc_stmt_get_col