PHP 手册
后退前进


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.

说明

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.

参数

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.

返回值

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

范例

例子 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"));

?>

参见

pg_execute()
pg_send_execute()


add a note add a note User Contributed Notes
scott dot marlowe at gmail dot com
07-Mar-2006 11:20
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 11:33
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 add a note


后退起点前进
pg_port上一级pg_put_line