odbc has a maximum buffer size, that means it only stores and retrieves a limited size of data to/from database each time. The maximum buffer size is 4096 and set in php.ini (odbc.defaultlrl). You can set it to higher value for larger data access.

Solid Issue:
Solid defines CHAR, VARCHAR, LONG VARCHAR, BINARY, VARBINARY, and LONG VARBINARY to be a maximum of 2G in length.  However, when creating your tables for use with PHP one should choose LONG VARCHAR or LONG VARBINARY for these kinds of fields if you are planning on storing really large or lengthy data.  IE: Data exceeding 64k in length such as GIF/JPG, or really huge text areas.

I have a solution for the problem with the strings beeing interpreted as filename because of the single quotes:

Just add a blank to the end of the string:

<?php
function odbc_escape_params ($params) {
 if (!is_array($params) or empty($params)) {
  return array();
 }
 foreach ($params as $key=>$val) {
  if (strlen($val) > 1 and $val{0} == "'" and $val{strlen($val)-1} == "'") {
   $params[$key] .= ' ';
  }
 }
 return $params;
}
?>

When odbc_execute() fails it returns FALSE and triggers a warning but it will not necessarily feed odbc_error() and odbc_errormsg().

In reply to cpoirier's note from 04-Mar-2001 03:30:

Currently, Access 2000 DOES support parametrized queries via ODBC. It still seems to have a problem with Memo and OLE fields, but "normal" types work just fine.

I don't think odbc_prepare and odbc_execute support output parameters for stored procedures on MSSQL.  An example of output parameters for MSSQL is at  http://support.microsoft.com/support/kb/articles/q174/2/23.asp

Also, my MSSQL driver seems happy only when I use the following incantation:

...code removed...
$stmt=odbc_prepare($conn_id, "exec my_proc_name ?,?,?"); 
$parms=array("fred","password",5);
if (!odbc_execute($stmt, &$parms)) die("odbc_execute failed");

When using odbc_execute to an MS Access database use single quotes (not double quotes) for literal string definitions.   

e.g. $sql = "Insert into [table] ([first], [last]) select 'Bob', 'Builder';"

If you use double quotes you may end up with an error like: [Microsoft] [ODBC Text Driver] Too few parameters. Expected: 2

If you want to use stored procedures with MSSQL over ODBC, please read 

http://www.sitepoint.com/article/php-microsoft-sql-server/2

It can you save lots of time ;)

When running the CGI version of 4.0.6 under windows, I came across this error when trying to call a stored procedure in SQL Server using odbc_execute w/ the parameter array set:

FATAL:  emalloc():  Unable to allocate 268675669 bytes

Scary error, huh? In my case it just meant that SQL Server couldn't find the stored procedure.  Totally my fault, but a rather nondescript error message.

p.

A quick note in hopes that my pain will save someone else:  Microsoft Access ODBC drivers do not support parameterized queries.

When used with parameters and the statement fails, you cannot use different arguments anymore, the same arguments as with the failed statement will be used.

I've been using odbc functions for quite a while and I was floored when I finally read the details about the how the parameters are handled when they start and end with single quotes! I assumed that the main reason for odbc_execute vs. odbc_exec was to prevent sql injection but apparently this added feature actually opens another security hole, perhaps worse. This was my fix:

<?php

function odbc_execute_clean_parameters($result_id, $parameters_array){
  for($i = 0; $i < count($parameters_array); ++$i){
    if( substr($parameters_array[$i], -1) == "'" && substr($parameters_array[$i], 0 ,1) == "'" ){
      $parameters_array[$i].= " ";
    }
  }
  return odbc_execute($result_id, $parameters_array);
}

// then call
$stmt = odbc_prepare($conn, " insert into mytable (col1, col2) values (?, ?) ");
$r = odbc_execute_clean_parameters($stmt, array( $val1, $val2 ) );

?>

Obdc_prepare and obdc_execute can only be used as an alternative to odbc_exec in limited circumstances:

$con = obdc_connect ($dsn, $user, $pass);
$sql = "select * from TABLE";

$result = obdc_exec ($con, $sql); //this line can be replaced as blow
//then to see results:

odbc_result_all ($result);
odbc_free_result ($result);
odbc_close ($con);

gives the same result with the middle line as:

$result = odbc_prepare ($con, $sql);
odbc_execute ($result);

as long as $sql contains a well formed and complete query.

There is no point in trying to convert this into a parameter query with question marks as placeholders, since code like this will result only in error messages:

$sql = "select * from TABLE where needle = ?";
$result = odbc_prepare ($con, $sql);
for ($i = 0; $i < 4; $i++)
{
  odbc_execute ($result, array ($i));
  // and whatever you want to do with the result
  // but all you get is "parameter expected" or "count does not match"
}

The lack of documentation for such functions should have been an alarm signal.

In reply to tcmleung at yahoo dot com (09-Nov-2001), I would add a caveat that I've found, which is that the odbc.defaultlrl/odbc_longreadlen() values may only apply to odbc->php conversion and not php->odbc (though this may be database-specific). Hence, if you want to post binary data the 4096 byte limit still stands. So you stand a better chance of being able to post binary data using the quoted filename upload procedure described above, rather than using the prepare... execute method with data held in a php variable.

Don't miss the part where it says that if your string starts and ends with a single quote, the string is interpreted as a filename!

This means that you can't do:

$sth = odbc_prepare($dbh, "INSERT INTO people(name) VALUES(?)");
$res = odbc_execute($sth, array($name));

without checking the value of $name--if $name is, say, '\\'c:\\passwords.txt\\'' the contents of c:\\passwords.txt get inserted into your database as a "name".

Also, despite what the documentation suggests, there (incredibly) doesn't appear to be any way to escape your single quotes (via experimentation, and from reading the source): if your string starts and ends with a single quote you cannot use odbc_execute to insert it into the database.

To use prepared with select queries, the right way is:
<?PHP

$rConnection = odbc_connect('AS400', 'QSECOFR', 'QSECOFR');
if($rConnection === false) {
    throw new ErrorException(odbc_errormsg());
}

$rResult = odbc_prepare($rConnection, 'SELECT * FROM KMNSH00F WHERE SHTMST > ?');
if($rResult === false) {
    throw new ErrorException(odbc_errormsg());
}

if(odbc_execute($rResult, array('0001-01-01 00:00:00.000000')) === false) {
    throw new ErrorException(odbc_errormsg());
}

odbc_result_all($rResult);

odbc_free_result($rResult);

odbc_close($rConnection);

?>

if you can't use php_mssql module in your environment (suse linux, apache2, php5, FreeTDS, unixODBC) an alternative is to use sql server functions instead of procedures. here is my sample code.

<?php
  $connect        = odbc_connect($myDB, $myUser, $myPass);

  $query = "SELECT dbo.<function>(<column>,<text>) alias";

  // perform the query
  $result = odbc_exec($connect, $query);

  while(odbc_fetch_row($result)) {
    $Var1    = odbc_result($result, <column alias>);
    //echo "Var1: " . $Var1 . "<br>";

        // add additional logic

  }
?>

Once I figured this out, my app worked perfectly.