A MySQL result set contains metadata. The metadata describes the columns
found in the result set. All metadata sent by MySQL is accessible
through the mysqli interface.
The extension performs no or negligible changes to the
information it receives.
Differences between MySQL server versions are not aligned.
Meta data is access through the mysqli_result interface.
Приклад #1 Accessing result set meta data
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");
$result = $mysqli->query("SELECT 1 AS _one, 'Hello' AS _two FROM DUAL");
var_dump($result->fetch_fields());Поданий вище приклад виведе:
array(2) {
[0]=>
object(stdClass)#3 (13) {
["name"]=>
string(4) "_one"
["orgname"]=>
string(0) ""
["table"]=>
string(0) ""
["orgtable"]=>
string(0) ""
["def"]=>
string(0) ""
["db"]=>
string(0) ""
["catalog"]=>
string(3) "def"
["max_length"]=>
int(1)
["length"]=>
int(1)
["charsetnr"]=>
int(63)
["flags"]=>
int(32897)
["type"]=>
int(8)
["decimals"]=>
int(0)
}
[1]=>
object(stdClass)#4 (13) {
["name"]=>
string(4) "_two"
["orgname"]=>
string(0) ""
["table"]=>
string(0) ""
["orgtable"]=>
string(0) ""
["def"]=>
string(0) ""
["db"]=>
string(0) ""
["catalog"]=>
string(3) "def"
["max_length"]=>
int(5)
["length"]=>
int(5)
["charsetnr"]=>
int(8)
["flags"]=>
int(1)
["type"]=>
int(253)
["decimals"]=>
int(31)
}
}
Prepared statements
Meta data of result sets created using prepared statements are accessed the same way. A suitable mysqli_result handle is returned by mysqli_stmt::result_metadata().
Приклад #2 Prepared statements metadata
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("example.com", "user", "password", "database");
$stmt = $mysqli->prepare("SELECT 1 AS _one, 'Hello' AS _two FROM DUAL");
$stmt->execute();
$result = $stmt->result_metadata();
var_dump($result->fetch_fields());See also