pg_select

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

pg_select — Select records

Description

pg_select(
    PgSql\Connection $connection,
    string $table_name,
    array $conditions = [],
    int $flags = PGSQL_DML_EXEC,
    int $mode = PGSQL_ASSOC
): array|string|false

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

If flags is set, pg_convert() is applied to conditions with the specified flags.

If mode is set, the return value will be in the form of an array with PGSQL_NUM, an associative array with PGSQL_ASSOC (default) or both with PGSQL_BOTH.

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 parameters/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: An PgSql\Connection instance.
table_name: Name of the table from which to select rows.
conditions: 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. As of PHP 8.4.0, when an empty array is provided, no conditions will apply. Previously, the function failed with an empty conditions argument.
flags: 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 flags then the query string is returned. When PGSQL_DML_NO_CONV or PGSQL_DML_ESCAPE is set, it does not call pg_convert() internally.
mode: Any number of PGSQL_ASSOC, PGSQL_NUM or PGSQL_BOTH If PGSQL_ASSOC is set the return value will be an associative array, with PGSQL_NUM the return value will be an array, and with PGSQL_BOTH the return value will be both an associative and numerically indexed array.

Return Values

Returns string if PGSQL_DML_STRING is passed via flags, otherwise it returns an array on success, or false on failure.

Changelog

Version	Description
8.4.0	`conditions` is now optional.
8.1.0	The `connection` parameter expects an PgSql\Connection instance now; previously, a resource was expected.
7.1.0	The `mode` parameter was added.

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 neither escape nor prepared query.
  $rec = pg_select($db, 'post_log', $_POST, PG_DML_ESCAPE);
  if ($rec) {
      echo "Records selected\n";
      var_dump($rec);
  } else {
      echo "User must have sent wrong inputs\n";
  }
?>

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User Contributed Notes 2 notes

down

david dot tulloh at infaze dot com dot au ¶

19 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.