db2_prepare
(PECL ibm_db2 >= 1.0.0)
db2_prepare — Prepares an SQL statement to be executed
Описание
$connection
, string $statement
[, array $options
] )db2_prepare() creates a prepared SQL statement which can include 0 or more parameter markers (? characters) representing parameters for input, output, or input/output. You can pass parameters to the prepared statement using db2_bind_param(), or for input values only, as an array passed to db2_execute().
There are three main advantages to using prepared statements in your application:
-
Performance: when you prepare a statement, the database server creates an optimized access plan for retrieving data with that statement. Subsequently issuing the prepared statement with db2_execute() enables the statements 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 markers for input values. When you execute a prepared statement with input values for placeholders, the database server checks each input value to ensure that the type matches the column definition or parameter definition.
-
Advanced functionality: Parameter markers not only enable you to pass input values to prepared SQL statements, they also enable you to retrieve OUT and INOUT parameters from stored procedures using db2_bind_param().
Список параметров
-
connection -
A valid database connection resource variable as returned from db2_connect() or db2_pconnect().
-
statement -
An SQL statement, optionally containing one or more parameter markers..
-
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().
Возвращаемые значения
Returns a statement resource 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().
Примеры
Пример #1 Preparing and executing an SQL statement with parameter markers
The following example prepares an INSERT statement that accepts four parameter markers, then iterates over an array of arrays containing the input values to be passed to db2_execute().
<?php
$animals = array(
array(0, 'cat', 'Pook', 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);
}
}
?>
Смотрите также
- db2_bind_param() - Binds a PHP variable to an SQL statement parameter
- db2_execute() - Executes a prepared SQL statement
- db2_stmt_error() - Returns a string containing the SQLSTATE returned by an SQL statement
- db2_stmt_errormsg() - Returns a string containing the last SQL statement error message
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для работы с базами данных
- Расширения для работы с базами данных отдельных производителей
- IBM DB2, Cloudscape and Apache Derby
- db2_autocommit
- db2_bind_param
- db2_client_info
- db2_close
- db2_column_privileges
- db2_columns
- db2_commit
- db2_conn_error
- db2_conn_errormsg
- db2_connect
- db2_cursor_type
- db2_escape_string
- db2_exec
- db2_execute
- db2_fetch_array
- db2_fetch_assoc
- db2_fetch_both
- db2_fetch_object
- db2_fetch_row
- db2_field_display_size
- db2_field_name
- db2_field_num
- db2_field_precision
- db2_field_scale
- db2_field_type
- db2_field_width
- db2_foreign_keys
- db2_free_result
- db2_free_stmt
- db2_get_option
- db2_last_insert_id
- db2_lob_read
- db2_next_result
- db2_num_fields
- db2_num_rows
- db2_pclose
- db2_pconnect
- db2_prepare
- db2_primary_keys
- db2_procedure_columns
- db2_procedures
- db2_result
- db2_rollback
- db2_server_info
- db2_set_option
- db2_special_columns
- db2_statistics
- db2_stmt_error
- db2_stmt_errormsg
- db2_table_privileges
- db2_tables
Коментарии
if you have the error message : PHP Warning: db2_prepare() [<a href='function.db2-prepare'>function.db2-prepare</a>]: Statement Prepare Failed in (....)and cannot display the error message using db2_stmt_errormsg() , then check if your database connection handle is (still) valid
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 get 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 work. You must only set that option on the prepare.
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]