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