# mysqli_result::fetch_fields

# mysqli_fetch_fields

(PHP 5, PHP 7, PHP 8)

mysqli_result::fetch_fields -- mysqli_fetch_fields — Returns an array of objects representing the fields in a result set

### 说明

面向对象风格

public mysqli_result::fetch_fields(): array

过程化风格

mysqli_fetch_fields(mysqli_result `$result`): array

This function serves an identical purpose to the mysqli_fetch_field() function with the single difference that, instead of returning one object at a time for each field, the columns are returned as an array of objects.

### 参数

`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。

### 返回值

Returns an array of objects containing field definition information.

Object properties
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

示例 #1 面向对象风格

`<?php
$mysqli = new mysqli("127.0.0.1", "root", "foofoo", "sakila");
/* check connection */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
foreach (array('latin1', 'utf8') as $charset) {
// Set character set, to show its impact on some values (e.g., length in bytes)
$mysqli->set_charset($charset);
$query = "SELECT actor_id, last_name from actor ORDER BY actor_id";
echo "======================\n";
echo "Character Set: $charset\n";
echo "======================\n";
if ($result = $mysqli->query($query)) {
/* Get field information for all columns */
$finfo = $result->fetch_fields();
foreach ($finfo as $val) {
printf("Name: %s\n", $val->name);
printf("Table: %s\n", $val->table);
printf("Max. Len: %d\n", $val->max_length);
printf("Length: %d\n", $val->length);
printf("charsetnr: %d\n", $val->charsetnr);
printf("Flags: %d\n", $val->flags);
printf("Type: %d\n\n", $val->type);
}
$result->free();
}
}
$mysqli->close();
?>`

示例 #2 过程化风格

`<?php
$link = mysqli_connect("127.0.0.1", "my_user", "my_password", "sakila");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
foreach (array('latin1', 'utf8') as $charset) {
// Set character set, to show its impact on some values (e.g., length in bytes)
mysqli_set_charset($link, $charset);
$query = "SELECT actor_id, last_name from actor ORDER BY actor_id";
echo "======================\n";
echo "Character Set: $charset\n";
echo "======================\n";
if ($result = mysqli_query($link, $query)) {
/* Get field information for all columns */
$finfo = mysqli_fetch_fields($result);
foreach ($finfo as $val) {
printf("Name: %s\n", $val->name);
printf("Table: %s\n", $val->table);
printf("Max. Len: %d\n", $val->max_length);
printf("Length: %d\n", $val->length);
printf("charsetnr: %d\n", $val->charsetnr);
printf("Flags: %d\n", $val->flags);
printf("Type: %d\n\n", $val->type);
}
mysqli_free_result($result);
}
}
mysqli_close($link);
?>`

以上示例会输出：

    ======================
    Character Set: latin1
    ======================
    Name:      actor_id
    Table:     actor
    Max. Len:  3
    Length:    5
    charsetnr: 63
    Flags:     49699
    Type:      2

    Name:      last_name
    Table:     actor
    Max. Len:  12
    Length:    45
    charsetnr: 8
    Flags:     20489
    Type:      253

    ======================
    Character Set: utf8
    ======================
    Name:      actor_id
    Table:     actor
    Max. Len:  3
    Length:    5
    charsetnr: 63
    Flags:     49699
    Type:      2

    Name:      last_name
    Table:     actor
    Max. Len:  12
    Length:    135
    charsetnr: 33
    Flags:     20489

### 参见

- mysqli_num_fields() - Gets the number of fields in the result set
- mysqli_fetch_field_direct() - Fetch meta-data for a single field
- mysqli_fetch_field() - Returns the next field in the result set

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