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Last updated: Sat, 27 Jan 2007

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# pg_prepare

(PHP 5 >= 5.1.0RC1)

pg_prepare -- Submits a request to create a prepared statement with the given parameters, and waits for completion.

## Описание

resource pg_prepare ( resource connection, string stmtname, string query )
resource pg_prepare ( string stmtname, string query )

pg_prepare() creates a prepared statement for later execution with pg_execute() or pg_send_execute(). This feature allows commands that will be used repeatedly to be parsed and planned just once, rather than each time they are executed. pg_prepare() is supported only against PostgreSQL 7.4 or higher connections; it will fail when using earlier versions.

The function creates a prepared statement named `stmtname` from the `query` string, which must contain a single SQL command. `stmtname` may be "" to create an unnamed statement, in which case any pre-existing unnamed statement is automatically replaced; otherwise it is an error if the statement name is already defined in the current session. If any parameters are used, they are referred to in the `query` as $1, $2, etc.

Prepared statements for use with pg_prepare() can also be created by executing SQL `PREPARE` statements. (But pg_prepare() is more flexible since it does not require parameter types to be pre-specified.) Also, although there is no PHP function for deleting a prepared statement, the SQL `DEALLOCATE` statement can be used for that purpose.

## Список параметров

`connection`

  PostgreSQL database connection resource. When `connection` is not present, the default connection is used. The default connection is the last connection made by pg_connect() or pg_pconnect().

`stmtname`

  The name to give the prepared statement. Must be unique per-connection. If "" is specified, then an unnamed statement is created, overwriting any previously defined unnamed statement.

`query`

  The parameterised SQL statement. Must contain only a single statement. (multiple statements separated by semi-colons are not allowed.) If any parameters are used, they are referred to as $1, $2, etc.

## Возвращаемые значения

A query result resource on success, or `FALSE` on failure.

## Примеры

Пример 1. Using pg_prepare()

`<?php
// Connect to a database named "mary"
$dbconn = pg_connect("dbname=mary");
// Prepare a query for execution
$result = pg_prepare($dbconn, "my_query", 'SELECT * FROM shops WHERE name = $1');
// Execute the prepared query. Note that it is not necessary to escape
// the string "Joe's Widgets" in any way
$result = pg_execute($dbconn, "my_query", array("Joe's Widgets"));
// Execute the same prepared query, this time with a different parameter
$result = pg_execute($dbconn, "my_query", array("Clothes Clothes Clothes"));
?>`

## Смотрите также

pg_execute()
pg_send_execute()

add a note User Contributed Notes
pg_prepare
rodrigo at fabricadeideias dot com
07-Nov-2006 04:05
`If you decide to deallocate (unprepare) a previously prepared sql command it might be better to quote the sql name as in
DEALLOCATE "theNameOfMySQL"
instead of (the more natural)
DEALLOCATE theNameOfMySQL
PostgerSQL preserves the case of your identifiers if, and only if, you quote them. The pg_prepare function preserves the case of the sql name you use.
A complete example would be
$sql = 'SELECT * FROM user WHERE cod_user = $1';
$sqlName = 'selectUserByCode';
if (!pg_prepare ($sqlName, $sql)) {
die("Can't prepare '$sql': " . pg_last_error());
}
$rs = pg_execute($sqlName, array(1));
do whatever you want with $rs and finally
$sql = sprintf(
'DEALLOCATE "%s"',
pg_escape_string($sqlName)
);
if(!pg_query($sql)) {
die("Can't query '$sql': " . pg_last_error());
}`
scott dot marlowe at gmail dot com
06-Mar-2006 07:20
`Note that if you are preparing a query with an in clause with a list of items, you will need to prepare each item separately.
$result = pg_prepare($dbconn, "my_query", 'SELECT * FROM shops WHERE name IN($1,$2,$3)');
$result = pg_execute($dbconn, "my_query", array("coffee", "beer", "hard"));
This means that you can't just prepare a query with an arbitrary in() list.`
david at fetter dot org
16-Apr-2005 08:33
`SQL is often a complicated piece of code by itself, so you may wish put it inside a "here doc." This will help you read it wherever it appears and test it by itself via a command-line or gui client.
$sql = <<<SQL
SELECT a.foo, b.bar, c.baz
FROM
table_a a
LEFT JOIN
table_b b
ON (
a.a_id = b.a_id
)
JOIN
table_c c
ON (
b.c_id = c.c_id
)
WHERE c.name = $1
SQL;`
add a note
pg_put_line pg_port

Last updated: Sat, 27 Jan 2007
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