International PHP Conference 2019 - Spring Edition

pg_select

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

pg_select Select records

Description

mixed pg_select ( resource $connection , string $table_name , array $assoc_array [, int $options = PGSQL_DML_EXEC [, int $result_type = PGSQL_ASSOC ]] )

pg_select() selects records specified by assoc_array which has field=>value. For a successful query, it returns an array containing all records and fields that match the condition specified by assoc_array.

If options is specified, pg_convert() is applied to assoc_array with the specified flags.

By default pg_select() passes raw values. Values must be escaped or PGSQL_DML_ESCAPE option must be specified. PGSQL_DML_ESCAPE quotes and escapes paramters/identifiers. Therefore, table/column names became case sensitive.

Note that neither escape nor prepared query can protect LIKE query, JSON, Array, Regex, etc. These parameters should be handled according to their contexts. i.e. Escape/validate values.

Parameters

connection

PostgreSQL database connection resource.

table_name

Name of the table from which to select rows.

assoc_array

An array whose keys are field names in the table table_name, and whose values are the conditions that a row must meet to be retrieved.

options

Any number of PGSQL_CONV_FORCE_NULL, PGSQL_DML_NO_CONV, PGSQL_DML_ESCAPE, PGSQL_DML_EXEC, PGSQL_DML_ASYNC or PGSQL_DML_STRING combined. If PGSQL_DML_STRING is part of the options then query string is returned. When PGSQL_DML_NO_CONV or PGSQL_DML_ESCAPE is set, it does not call pg_convert() internally.

Return Values

Returns TRUE on success or FALSE on failure. Returns string if PGSQL_DML_STRING is passed via options.

Examples

Example #1 pg_select() example

<?php 
  $db 
pg_connect('dbname=foo');
  
// This is safe somewhat, since all values are escaped.
  // However PostgreSQL supports JSON/Array. These are not
  // safe by nither escape nor prepared query.
  
$rec pg_select($db'post_log'$_POSTPG_DML_ESCAPE);
  if (
$rec) {
      echo 
"Records selected\n";
      
var_dump($rec);
  } else {
      echo 
"User must have sent wrong inputs\n";
  }
?>

Changelog

Version Description
7.1.0 The result_type parameter was added.
5.6.0 No longer experimental. Added PGSQL_DML_ESCAPE constant, TRUE/FALSE and NULL data type support.
5.5.3/5.4.19 Direct SQL injection to table_name and Indirect SQL injection to identifiers are fixed.

See Also

  • pg_convert() - Convert associative array values into forms suitable for SQL statements

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User Contributed Notes 2 notes

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0
david dot tulloh at infaze dot com dot au
13 years ago
Valid options are PGSQL_DML_NO_CONV, PGSQL_DML_EXEC, PGSQL_DMP_ASYNC, PGSQL_DML_STRING (pulled out of source code).

This function does not support selecting from multiple tables.  You can get around this by setting the PGSQL_DML_NO_CONV option.  This prevents the error which occurs when the function tries to convert the condition array.

I think it is also important to point out that the table_name field is not safe, particularily with the PGSQL_DML_NO_CONV option.

The arguements array field is compulsory, as documented.  What isn't so clear is that the array has to actually have some values in it, you can't do a select all.

In summary, this function is good for a very small subset of basic queries.  If you are after anything more complex you are better off with pg_query.
up
-3
wietse at cj2 dot nl
12 years ago
David mentioned that you can't do a Select all.
However, when executing this script:
<?php
    $conn_string
= "dbname=mydb";
   
$db = pg_connect($conn_string);
   
$selectfields = array("imgid" => "");
   
$records = pg_select($db,"mmsfiles",$selectfields);
   
print_r($records);
?>
...I get this result:
Array
(
    [0] => Array
        (
            [imgid] => 1
            [file] => /home/wietse/public_html/mms/images/1.gif
            [thumb] =>
        )
    [1] => Array
        (
            [imgid] => 2
            [file] => /home/wietse/public_html/mms/images/2.gif
            [thumb] =>
        )
    [2] => Array
        (
            [imgid] => 3
            [file] => /home/wietse/public_html/mms/images/3.gif
            [thumb] =>
        )
    [3] => Array
        (
            [imgid] => 4
            [file] => /home/wietse/public_html/mms/images/4.gif
            [thumb] =>
        )
)
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