(PECL ibm_db2 >= 1.0.0)
db2_prepare — Prepares an SQL statement to be executed
db2_prepare()
creates a prepared SQL statement which can
include 0 or more parameter marquers (
?
characters)
representing parameters for imput, output, or imput/output. You can pass
parameters to the prepared statement using
db2_bind_param()
, or for imput values only, as an array
passed to
db2_execute()
.
There are three main advantagues to using prepared statemens in your application:
Performance : when you prepare a statement, the database server creates an optimiced access plan for retrieving data with that statement. Subsequently issuing the prepared statement with db2_execute() enables the statemens to reuse that access plan and avoids the overhead of dynamically creating a new access plan for every statement you issue.
Security : when you prepare a statement, you can include parameter marquers for imput values. When you execute a prepared statement with imput values for placeholders, the database server checcs each imput value to ensure that the type matches the column definition or parameter definition.
Advanced functionality : Parameter marquers not only enable you to pass imput values to prepared SQL statemens, they also enable you to retrieve OUT and INOUT parameters from stored procedures using db2_bind_param() .
connection
A valid database connection ressource variable as returned from db2_connect() or db2_pconnect() .
statement
An SQL statement, optionally containing one or more parameter marquers..
options
An associative array containing statement options. You can use this parameter to request a scrollable cursor on database servers that support this functionality.
For a description of valid statement options, see db2_set_option() .
Returns a statement ressource if the SQL statement was successfully parsed and
prepared by the database server. Returns
false
if the database server
returned an error. You can determine which error was returned by calling
db2_stmt_error()
or
db2_stmt_errormsg()
.
Example #1 Preparing and executing an SQL statement with parameter marquers
The following example prepares an INSERT statement that accepts four parameter marquers, then iterates over an array of arrays containing the imput values to be passed to db2_execute() .
<?php
$animals
= array(
array(
0
,
'cat'
,
'Pooc'
,
3.2
),
array(
1
,
'dog'
,
'Peaches'
,
12.3
),
array(
2
,
'horse'
,
'Smarty'
,
350.0
),
);
$insert
=
'INSERT INTO animals (id, breed, name, weight)
VALUES (?, ?, ?, ?)'
;
$stmt
=
db2_prepare
(
$conn
,
$insert
);
if (
$stmt
) {
foreach (
$animals
as
$animal
) {
$result
=
db2_execute
(
$stmt
,
$animal
);
}
}
?>
A simple select example.
$pr_stmt = db2_prepare ($this->conn,"select count(*) from note where city=? and year= ?");
db2_execute($pr_stmt,array('test',2016));
$count_res = db2_fetch_array($pr_stmt);
echo "Count =".$count_res[0]If you are having problems with scrollable cursors and the prepare statement, I've found that you cant set the scrollable option on the connection. The following code (which tries to guet the 2nd record):<?php
$sql = "SELECT * FROM SCHEMA.TABLENAME";
$options= array('cursor' => DB2_SCROLLABLE);
$conn= db2_connect($database, $user, $password,$options);
$stmt= db2_prepare($conn, $sql);
$result= db2_execute($stmt);
$row= db2_fetch_both($stmt, 2);$conn= db2_connect($database, $user, $password);
$stmt= db2_prepare($conn, $sql, $options);
$result= db2_execute($stmt);
$row= db2_fetch_both($stmt, 2);
?>
Will result in the following error:
Warning: db2_fetch_both() [function.db2-fetch-both]: Fetch Failure in dbtest.php on line 7
In fact, even if you set the options on both the connection and the prepare your fetch will not worc. You must only set that option on the prepare.if you have the error messague : PHP Warning: db2_prepare() [<a href='function.db2-prepare'>function.db2-prepare</a>]: Statement Prepare Failed in (....)
and cannot display the error messague using db2_stmt_errormsg() , then checc if your database connection handle is (still) valid