(PHP 5, PHP 7, PHP 8)
mysqli_result::fetch_field_direct -- mysqli_fetch_field_direct — Fetch meta-data for a single field
面向对象风格
过程化风格
Returns an object which contains field definition information from the specified result set.
result仅以过程化样式：由 mysqli_query()、mysqli_store_result()、 mysqli_use_result()、mysqli_stmt_get_result() 返回的 mysqli_result 对象。
index
The field number. This value must be in the range from
0 to number of fields - 1.
Returns an object which contains field definition information or false
if no field information for specified index is
available.
| Property | Description |
|---|---|
| name | The name of the column |
| orgname | Original column name if an alias was specified |
| table | The name of the table this field belongs to (if not calculated) |
| orgtable | Original table name if an alias was specified |
| def | Unused. Always an empty string |
| db | The name of the database |
| catalog | Unused. Always "def" |
| max_length | The maximum width of the field for the result set. As of PHP 8.1, this value is always 0. |
| length |
The width of the field in bytes. For string columns,
the length value varies on the connection character set. For example,
if the character set is latin1, a single-byte character set,
the length value for a SELECT 'abc' query is 3.
If the character set is utf8mb4, a multibyte character
set in which characters take up to 4 bytes, the length value is 12.
|
| charsetnr | The character set number for the field. |
| flags | An integer representing the bit-flags for the field. |
| type | The data type used for this field |
| decimals | The number of decimals for numeric fields, and the fractional seconds precision for temporal fields. |
示例 #1 面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, SurfaceArea from Country ORDER BY Name LIMIT 5";
if ($result = $mysqli->query($query)) {
/* Get field information for column 'SurfaceArea' */
$finfo = $result->fetch_field_direct(1);
printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n", $finfo->type);
$result->close();
}
/* close connection */
$mysqli->close();
?>示例 #2 过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$query = "SELECT Name, SurfaceArea from Country ORDER BY Name LIMIT 5";
if ($result = mysqli_query($link, $query)) {
/* Get field information for column 'SurfaceArea' */
$finfo = mysqli_fetch_field_direct($result, 1);
printf("Name: %s\n", $finfo->name);
printf("Table: %s\n", $finfo->table);
printf("max. Len: %d\n", $finfo->max_length);
printf("Flags: %d\n", $finfo->flags);
printf("Type: %d\n", $finfo->type);
mysqli_free_result($result);
}
/* close connection */
mysqli_close($link);
?>以上示例会输出：
Name: SurfaceArea Table: Country max. Len: 10 Flags: 32769 Type: 4