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(PHP 5)
mysqli_stmt::result_metadata -- mysqli_stmt_result_metadata — Returns result set metadata from a prepared statement
面向对象风格
过程化风格
$stmt
)If a statement passed to mysqli_prepare() is one that produces a result set, mysqli_stmt_result_metadata() returns the result object that can be used to process the meta information such as total number of fields and individual field information.
Note:
This result set pointer can be passed as an argument to any of the field-based functions that process result set metadata, such as:
mysqli_num_fields()
mysqli_fetch_field()
mysqli_fetch_field_direct()
mysqli_fetch_fields()
mysqli_field_count()
mysqli_field_seek()
mysqli_field_tell()
mysqli_free_result()
The result set structure should be freed when you are done with it, which you can do by passing it to mysqli_free_result()
Note:
The result set returned by mysqli_stmt_result_metadata() contains only metadata. It does not contain any row results. The rows are obtained by using the statement handle with mysqli_stmt_fetch() .
stmt
仅以过程化样式:由 mysqli_stmt_init() 返回的 statement 标识。
Returns a result object or FALSE
if an error occurred.
Example #1 面向对象风格
<?php
$mysqli = new mysqli ( "localhost" , "my_user" , "my_password" , "test" );
$mysqli -> query ( "DROP TABLE IF EXISTS friends" );
$mysqli -> query ( "CREATE TABLE friends (id int, name varchar(20))" );
$mysqli -> query ( "INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')" );
$stmt = $mysqli -> prepare ( "SELECT id, name FROM friends" );
$stmt -> execute ();
$result = $stmt -> result_metadata ();
$field = $result -> fetch_field ();
printf ( "Fieldname: %s\n" , $field -> name );
$result -> close ();
$mysqli -> close ();
?>
Example #2 过程化风格
<?php
$link = mysqli_connect ( "localhost" , "my_user" , "my_password" , "test" );
mysqli_query ( $link , "DROP TABLE IF EXISTS friends" );
mysqli_query ( $link , "CREATE TABLE friends (id int, name varchar(20))" );
mysqli_query ( $link , "INSERT INTO friends VALUES (1,'Hartmut'), (2, 'Ulf')" );
$stmt = mysqli_prepare ( $link , "SELECT id, name FROM friends" );
mysqli_stmt_execute ( $stmt );
$result = mysqli_stmt_result_metadata ( $stmt );
$field = mysqli_fetch_field ( $result );
printf ( "Fieldname: %s\n" , $field -> name );
mysqli_free_result ( $result );
mysqli_close ( $link );
?>
[#1] potherca at gmail dot com [2010-04-15 00:52:18]
If result_metadata() returns false but error/errno/sqlstate tells you no error occurred, this means your query is one that does not produce a result set, i.e. an INSERT/UPDATE/DELETE query instead of a SELECT query.
This is stated in the documentation where it says "If a statement passed to mysqli_prepare() is one that produces a result set, mysqli_stmt_result_metadata() returns the result object", but it might not be clear to everyone what this entails exactly.
Hope this helps.