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mysqli::$field_count

mysqli_field_count

(PHP 5)

mysqli::$field_count -- mysqli_field_count — 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

int mysqli_field_count ( mysqli $link )

Returns the number of columns for the most recent query on the connection represented by the link parameter. 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_count example

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);
?>
MySQLi
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PHP手册
PHP手册 - N: Returns the number of columns for the most recent query

用户评论:

Jonathan (06-Mar-2007 11:43)

Some corrections ;o)

$mysqli_type = array();
$mysqli_type[0] = "DECIMAL";
$mysqli_type[1] = "TINYINT";
$mysqli_type[2] = "SMALLINT";
$mysqli_type[3] = "INTEGER";
$mysqli_type[4] = "FLOAT";
$mysqli_type[5] = "DOUBLE";

$mysqli_type[7] = "TIMESTAMP";
$mysqli_type[8] = "BIGINT";
$mysqli_type[9] = "MEDIUMINT";
$mysqli_type[10] = "DATE";
$mysqli_type[11] = "TIME";
$mysqli_type[12] = "DATETIME";
$mysqli_type[13] = "YEAR";
$mysqli_type[14] = "DATE";

$mysqli_type[16] = "BIT";

$mysqli_type[246] = "DECIMAL";
$mysqli_type[247] = "ENUM";
$mysqli_type[248] = "SET";
$mysqli_type[249] = "TINYBLOB";
$mysqli_type[250] = "MEDIUMBLOB";
$mysqli_type[251] = "LONGBLOB";
$mysqli_type[252] = "BLOB";
$mysqli_type[253] = "VARCHAR";
$mysqli_type[254] = "CHAR";
$mysqli_type[255] = "GEOMETRY";

Typer85 at gmail dot com (02-Jan-2007 04:33)

For those interested and to clarify the Manual Entry.

For query statements that are DESIGNED to return a result set of some sort, this function will always return the number of fields in the table that was queried.

I said DESIGNED because the return value has no effect on whether or not the actual query matched any rows or not.

For example, say I have a table that has 2 fields and only 10 rows. I issue the following query:

<?php

// Assume Connection Blah Blah.

mysqli_query( $connObject , "Select * From `table` Where `Id` > 1000");

// Get Number Of Fields.

mysqli_field_count( $connObject );

// Will Return 2 --> The Number of fields in the table!

?>

It is quite clear that the query itself will never return a result set because I asked it to return rows which have an Id over 1000 and there are only 10 rows.

But because the nature of the query itself is to return a result set, the field count is always returned no matter what.

In contrast, if the query does anything that does not return a result set by nature, such as an insert or update, the field count will always be 0.

Hence, you can easily determine the nature of this query dynamically using these return values.

Good Luck,

?>

dedlfix (18-Jul-2006 06:26)

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

jakerosoft at hotmail dot com (16-Aug-2005 05:15)

<?
$fieldinfo = $result->fetch_field();
if ($fieldinfo & MYSQLI_NOT_NULL_FLAG)  {
  print "not null flag is set";
} else {
  print "not null flag is NOT set";
}
?>

Marc-Andr (07-Jul-2005 11:56)

The "type" property will return a numerical representation of a field type instead of a "meaningful" string.

Here is an array that may help you:

<?php
$mysqli_type = array();
$mysqli_type[0] = "decimal";
$mysqli_type[1] = "tinyint";
$mysqli_type[2] = "smallint";
$mysqli_type[3] = "int";
$mysqli_type[4] = "float";
$mysqli_type[5] = "double";
$mysqli_type[7] = "timestamp";
$mysqli_type[8] = "bigint";
$mysqli_type[9] = "mediumint";
$mysqli_type[10] = "date";
$mysqli_type[11] = "time";
$mysqli_type[12] = "datetime";
$mysqli_type[13] = "year";
$mysqli_type[252] = "blob"; // text, blob, tinyblob,mediumblob, etc...
$mysqli_type[253] = "string"; // varchar and char
$mysqli_type[254] = "enum";
?>