(no version information, might be only in CVS)

pg_prepare -- Prepares a query for future execution


resource pg_prepare ( string stmtname, string query )

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

pg_prepare() returns a query result resource if query could be prepared. It returns FALSE on failure or if connection is not a valid connection. Details about the error can be retrieved using the pg_last_error() function if connection is valid. pg_prepare() prepares an SQL statement for the PostgreSQL database connection specified by the connection resource. The connection must be a valid connection that was returned by pg_connect() or pg_pconnect(). The return value of this function is an query result resource. The stmtname is the name of the prepared query, for future use with pg_execute() or pg_send_execute().

Note : connection is an optional parameter for pg_prepare(). If connection is not set, default connection is used. Default connection is the last connection made by pg_connect() or pg_pconnect().

Although connection can be omitted, it is not recommended, since it could be a cause of hard to find bug in script.

Parameters to pg_prepare() are specified using placeholders in the query. It is not necessary to quote parameters as quoting and escaping is done automatically. Placeholders are indicated in the query by $1, $2, $3 and so on.

Using prepared queries means you can prepare one and then execute many times, with different parameters. PostgreSQL will cache the query plan on the prepare, then re-use it for each execute, resulting in speed improvements. There is no need to use a prepared query if it will only be executed once. In this case, it is simpler to use pg_query_params().


Exemple 1. Using pg_prepare()

// 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"));


Voir aussi