mysqli_stmt::result_metadata

mysqli_stmt_result_metadata

(PHP 5)

mysqli_stmt::result_metadata -- mysqli_stmt_result_metadata — Returns result set metadata from a prepared statement

说明

面向对象风格

mysqli_result mysqli_stmt::result_metadata ( void )

过程化风格

mysqli_result mysqli_stmt_result_metadata ( mysqli_stmt $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() .

参数

stmt: 仅以过程化样式：由 mysqli_stmt_init() 返回的 statement 标识。

返回值

Returns a result object or FALSE if an error occurred.

范例

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 );
 ?>

参见

mysqli_prepare() - Prepare an SQL statement for execution
mysqli_free_result() - Frees the memory associated with a result

用户评论:

[#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.