odbc_result

Here's a limitation that isn't mentioned anywhere (that I could see) and gave me a rather large headache for a couple of hours trying to figure out why my database wasn't initializing correctly.
If you are trying to retrieve a large collection of fields from a database, be aware that odbc_result may only return up to 33 result columns.  Any more than that, and it generates a "result out of range" warning in your script.
(I tried adjusting to have 32 fields, with the same bug.) It generates an error "Warning: Field index is larger than the number of fields inyour-script.php on line 70" ANY time you try to retrieve the last field of a sufficiently large record. What worked for me was just to write the last column twice... that way, the query has 34 fields, but the last two are the same. You know it'll crash if you ask for #34, but just use ODBC_result(current_query, 33) and you won't have a problem. Good luck

-D

The odbc_result() function has an apparently little known feature that comes in very handy when retrieving large text or binary fields.Consider this code snippet to retrieve a large value into a temporary file (error testing left out for clarity):<?php$con=odbc_connect(...);$query="set textsize 2147483647 ".       "select someLargeField from ...";$resultset=odbc_exec($con,$query);odbc_binmode($resultset,ODBC_BINMODE_RETURN);odbc_longreadlen($resultset,4096);while (odbc_fetch_row($resultset)) {   $fileHandle=fopen('/tmp/myfile','wb');   while (($chunk=odbc_result($resultset,'someLargeField'))!==false) {      fwrite($fileHandle,$chunk);   }   fclose($fileHandle);   //do something with the file}?>There are a few key points to make it work:- Make sure to include "set textsize 2147483647 " in your query.  Without it, MSSQL truncates large values to 4096 bytes by default.  Other databases may have a similar small limit.- The odbc_binmode() and odbc_longreadlen() calls are just for safety.  Their defaults in php.ini are usually correct.- Each odbc_result() call on a large field apparently returns the next chunk.  Of course you have to read all chunks before the next odbc_fetch_row() call.- When all of the large value has been read, odbc_result() will return false.Note: Using mssql_ instead of odbc_ functions is not a viable alternative. They don't work with chunks (AFAIK) and even crash php (overflow, segmentation fault) when the query result contains a large value.

From http://www.php.net/manual/en/function.odbc-longreadlen.php but relevant here, also. An alternative is to adjust your php.ini file and set:odbc.defaultlrl=65536Or something else sufficiently large.lrl = long read lengthto get around the limit on returned chars.

Hopefully useful note on accessing TEXT fields on Windows, using PHP's ODBC support to access Sybase*. With the following code:

"SELECT status AS projstatus,oid AS projident,LOWER(title) AS projtitel,startsOn AS projanfang,terminatesOn AS projende,description AS projinfo FROM Project ORDER BY projtitel ASC"

I was getting a strange error:

  Warning: SQL error: [INTERSOLV][ODBC SQL Server driver][SQL Server]Invalid column name 'projanfang'. , SQL state S0022 in SQLGetData in [**scriptname and path removed**] on line 126

even though I was clearly selecting a field as 'projanfang'. The reason I worked out eventually is that Sybase/ODBC attempts to do a conversion on the TEXT field 'description', which fails since the limit for CONVERT is 255 characters, and TEXT is a field type with a  2 GB limit. I am not sure why it doesn't work implicitly, but it does explicitly. The following code will work without errors:

  "SELECT status AS projstatus,oid AS projident,LOWER(title) AS projtitel,startsOn AS projanfang,terminatesOn AS projende,CONVERT(CHAR(255),description) AS projinfo FROM Project ORDER BY projtitel ASC"

What you do if you have a need for more than 255 characters of your text field, I do not know :(. I have also tried longreadlen, but I couldn't work out how it could be used.

* System details: Windows NT 4.0 SP6a, IIS 4.0, Sybase 11.5 Adaptive Enteprise, PHP 4.0.5.

When trying to get a date/time field from an Access database, odbc_result returns the date as text (e.g. 1998-07-11 21:12:23). You may use strtotime function to convert this into a format which can be used with PHP.e.g.echo "The date is " .date("r",strtotime(odbc_result($myquery,"mydate")));

Problem: Function returns a max of 4095 bytes of a cell with one call.

Tip: If you have a cell containing more than 4095 bytes, write a loop and call the cell over and over as long return is not "". All returns can be added up to the whole string.

FWIW, ADO and similar ODBC-using interfaces also cannot distinguish between A.id and B.id. The easy solution is aliasing in SQL:

Consider a table "A" consisting only of the column "id". Next, consider the following query:

SELECT * FROM A JOIN B ON A.id=B.id

With ODBC, you'd be forced to use the numerical index, rather than the name. However, you could rewrite the query, too:

SELECT A.id AS A_id, B.id AS B_id FROM A JOIN B ON A.id=B.id

This can be better on three counts:

Firstly, unless you really want everything in the result set, it might be faster. SQL servers can be faster with "*", but often the networking will benefit from less data (Or a smaller tuple width, if you're into database jargon).

Secondly, since you're forced into thinking about what you want out of the query, you'll probably write better SQL as a result.

Thirdly, if you change the query - or tables - slightly, you don't have to revisit all your code to cope with the change.

Aplogies for stating the obvious, and having no imagination with my examples.

Beware if you have fields with the same name in a result

<?php 
$res = odbc_exec($conn,"select * from PeopleMR,People,Role,Organisation".
" WHERE PeopleMR.MeetingID = $MeetingID" .
" ORDER BY People.Surname");
?>

I have the field "Name" from both TABLE Role and TABLE Organisation, as for MySQL you would do :

<?php
mysql_result($res,$count,"Role.Name");   
mysql_result($res,$count,"Organisation.Name");
?>

but with odbc you do :

<?php odbc_result($res,$count,"Name"); ?>

this gives you the result of TABLE Role "Name" so you have to find the Field Number for the Organisation"Name" to have the correct result.

if you want to quickly change a website from odbc- to mysql-data-access, you could use a simple function like this one:function myresult ($cur,$nr) {    return mysql_result($cur,0,mysql_field_name($cur,$nr-1)); }and just do a global replace from "odbc_result" to "myresult".beware, you should only use this if you don't care too much about performance, as this will start a query for every field you request - the better way is of course using mysql_fetch_row!

With an Access 2K database, odbc_result will only work the first time it is called on a memo field (odbc_field_type returns 'LONGCHAR').

$good = odbc_result($result,'Description');
# $good holds the field value
$fail = odbc_result($result,'Description');
# $fail holds false

This tripped me up when I did something like this:

for ($i=1; $i<=odbc_num_fields($result); $i++) {
  if(odbc_result($result,$i)){
    ... more code ...
    echo odbc_result($result,$i);
    ... snip ...
  }
}

For any field type except memo, this code works perfectly.  But on memo fields, odbc_result returns false on the second call and nothing is echoed.

Be careful, use a temporary variable instead of multiple calls to odbc_result.  (It's good programming practice anyway)

for (...) {
  $temp = odbc_result($result,$i);
  if($temp){
    ...
    echo $temp;
    ...
  }
}

I use one store procedure to retrieve value of identifier, other, name, section,data and datecreated coulmns to variable from SQL server table using $odbc_result = odbc_exec($connect,$query); function.After that, I using following code,for($f=1;$f<=odbc_num_fields($odbc_result);$f++) {echo "<td style=\"font-weight:bold\">$f ".odbc_field_name($odbc_result,$f)."</td>";}echo "</tr></table>";odbc_fetch_row($odbc_result);echo odbc_result($odbc_result,1)."<br>";echo odbc_result($odbc_result,2)."<br>";echo odbc_result($odbc_result,3)."<br>";echo odbc_result($odbc_result,4)."<br>";echo odbc_result($odbc_result,5)."<br>";echo odbc_result($odbc_result,6)."<br>";The result is as following,1 identifier 2 other 3 name 4 section 5 data 6 datecreated id1other2name3section4Warning: odbc_result() [function.odbc-result]: SQL error: [Microsoft][ODBC SQL Server Driver]Invalid Descriptor Index, SQL state S1002 in SQLGetData in d:\lawdepot_test\contracts\common\LicensingSQL.php on line 6302005-03-16 18:12:00I can not get "data"(Text column) back. Firstly, I think "data" column is too long for odbc_result($odbc_result,5) function, but after I check my old colde, I found I can get the "data" back using same function odbc_result().I would like to hear any suggestions from you. Depressed on this question.Michael

i use odbc and mysql and i noticed after losing a lot of time that if you write something like this:echo odbc_result($result,1); ....echo odbc_result($result,1);the second echo will fail. so it's more useful to save the result of odbc_result in a variable and use it laterlike that: $var=odbc_result($result,1);i hope this will be useful!

FYI: odbc_result contains the following values: TABLE_QUALIFIER    TABLE_OWNER    TABLE_NAME    COLUMN_NAME    DATA_TYPE    TYPE_NAME    PRECISION    LENGTH    SCALE    RADIX    NULLABLE    REMARKS    COLUMN_FLAGSI wrote the following to dump these values onto the page. I needed this to determine if the data-type for a column was something specific (eg: blob) to show a different result, instead of the actual contents.         $connection_string = 'OPTIM_BLOB';        $user = '';        $pass = '';                if (!($connect = odbc_pconnect($connection_string, $user, $pass))) {                    } else {            echo 'Connecting to DSN, loading tables<br /><br />';            $result = odbc_tables($myconn);            $tables = array();            while (odbc_fetch_row($result)){                if(odbc_result($result,"TABLE_TYPE")=="TABLE") {                    $TableName = odbc_result($result,"TABLE_NAME");                    echo '<span id="tableName">Table: '.$TableName.'</span> ....<br /><br /> ';                    //--------- Show Columns in that table ---------------                    $result2 = odbc_columns($myconn, '', "%", $TableName, "%");  //db connection, DB name, schema, table name, column_name);                    while(odbc_fetch_row($result2)){                        //TABLE_QUALIFIER    TABLE_OWNER    TABLE_NAME    COLUMN_NAME    DATA_TYPE    TYPE_NAME    PRECISION    LENGTH    SCALE    RADIX    NULLABLE    REMARKS    COLUMN_FLAGS                                                $COLUMN_NAME = odbc_result($result2, 4); // COLUMN_NAME                        $DataType = odbc_result($result2, 6);                        echo '<b>Column name: '.$COLUMN_NAME.'</b> Type: '.$DataType.'<br /><br />';                        // everything                        echo '1: '.odbc_result($result2, 1).'<br />';    // TABLE_QUALIFIER                        echo '2: '.odbc_result($result2, 2).'<br />';    // TABLE_OWNER                        echo '3: '.odbc_result($result2, 3).'<br />';    // TABLE_NAME                        echo '4: '.odbc_result($result2, 4).'<br />';    // COLUMN_NAME                        echo '5: '.odbc_result($result2, 5).'<br />';    // DATA_TYPE (Number)                        echo '6: '.odbc_result($result2, 6).'<br />';    // TYPE_NAME (String)                        echo '7: '.odbc_result($result2, 7).'<br />';    // PRECISION                        echo '8: '.odbc_result($result2, 8).'<br />';    // LENGTH                        echo '9: '.odbc_result($result2, 9).'<br />';    // SCALE                        echo '10: '.odbc_result($result2, 10).'<br />';    // RADIX                        echo '11: '.odbc_result($result2, 11).'<br />';    // NULLABLE                        echo '12: '.odbc_result($result2, 12).'<br />';    // REMARKS                        echo '13: '.odbc_result($result2, 13).'<br />';    // COLUMN_FLAGS                        echo '<br /><br />';                    }                }            }        }