mysqli::$field_count()

(PHP 5, PHP 7)

Returns the number of columns for the most recent query

说明

面向对象风格
int $mysqli->field_count;

过程化风格
mysqli_field_count(mysqli$link): int

Returns the number of columns for the most recent query on the connection represented by the$linkparameter. This function can be useful when using the mysqli_store_result() function to determine if the query should have produced a non-empty result set or not without knowing the nature of the query.

参数

$link

仅以过程化样式：由mysqli_connect()或mysqli_init()返回的链接标识。

返回值

An integer representing the number of fields in a result set.

范例

Example #1$mysqli->field_countexample

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')");
$mysqli->real_query("SELECT * FROM friends");
if ($mysqli->field_count) {
    /* this was a select/show or describe query */
    $result = $mysqli->store_result();
    /* process resultset */
    $row = $result->fetch_row();
    /* free resultset */
    $result->close();
}
/* close connection */
$mysqli->close();
?>

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')");
mysqli_real_query($link, "SELECT * FROM friends");
if (mysqli_field_count($link)) {
    /* this was a select/show or describe query */
    $result = mysqli_store_result($link);
    /* process resultset */
    $row = mysqli_fetch_row($result);
    /* free resultset */
    mysqli_free_result($result);
}
/* close connection */
mysqli_close($link);
?>

There are MYSQLI_TYPE_* constants for the type property (listed in http://php.net/manual/en/ref.mysqli.php).
e.g.
<?php
if ($finfo->type == MYSQLI_TYPE_VAR_STRING)
 // a VARCHAR