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PHP5中文手册
mysqli
PHP Manual

mysqli_num_fields

result->field_count

(No version information available, might be only in CVS)

result->field_count — Get the number of fields in a result

说明

Procedural style:

int mysqli_num_fields ( mysqli_result $result )

Object oriented style (property):

mysqli_result
int$field_count;

Returns the number of fields from specified result set.

参数

result

Procedural style only: A result set identifier returned by mysqli_query(), mysqli_store_result() or mysqli_use_result().

返回值

The number of fields from a result set.

范例

Example#1 Object oriented style

<?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();
}

if ($result = $mysqli->query("SELECT * FROM City ORDER BY ID LIMIT 1")) {

    /* determine number of fields in result set */
    $field_cnt = $result->field_count;

    printf("Result set has %d fields.\n", $field_cnt);

    /* close result set */
    $result->close();
}

/* close connection */
$mysqli->close();
?>

Example#2 Procedural style

<?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();
}

if ($result = mysqli_query($link, "SELECT * FROM City ORDER BY ID LIMIT 1")) {

    /* determine number of fields in result set */
    $field_cnt = mysqli_num_fields($result);

    printf("Result set has %d fields.\n", $field_cnt);

    /* close result set */
    mysqli_free_result($result);
}

/* close connection */
mysqli_close($link);
?>

上例将输出：

Result set has 5 fields.

参见

mysqli
PHP Manual