(PHP 4, PHP 5)
mysql_result — 取得结果数据
mysql_result() 返回 MySQL 结果集中一个单元的内容。字段参数可以是字段的偏移量或者字段名，或者是字段表点字段名（tablename.fieldname）。如果给列起了别名（'select foo as bar from...'），则用别名替代列名。
当作用于很大的结果集时，应该考虑使用能够取得整行的函数（在下边指出）。这些函数在一次函数调用中返回了多个单元的内容，比 mysql_result() 快得多。此外注意在字段参数中指定数字偏移量比指定字段名或者 tablename.fieldname 要快得多。
调用 mysql_result() 不能和其它处理结果集的函数混合调用。
Example #1 mysql_result() 例子
<?php
$link = mysql_connect("localhost", "mysql_user", "mysql_password")
or die("Could not connect: " . mysql_error());
$result = mysql_query("SELECT name FROM work.employee")
or die("Could not query: . mysql_error());
echo mysql_result($result,2); // outputs third employee's name
mysql_close($link);
?>
推荐使用高性能的替代函数： mysql_fetch_row()， mysql_fetch_array()， mysql_fetch_assoc() 和 mysql_fetch_object()。
bruce at kaskubar dot com (2011-04-29 06:30:02)
The warning against mixing the use of mysql_result with other result set functions is a bit generic. More specifically, mysql_result alters the result set's internal row pointer (at least in a LAMP environment). This is anything but obvious as the nature of the function is random access for grabbing a quick byte. Using mysql_data_seek after some mysql_result calls, before going into a mysql_fetch_array loop, will set things straight.
DJK (2009-10-06 14:00:12)
Note that mysql_result affects the internal pointer used by mysql_fetch_*
<?php
$res = mysql_query('SELECT a,b FROM ab');
echo mysql_result($res,0,0);
print_r(mysql_fetch_assoc($res));
?>
In the above example, the call to mysql_fetch_assoc would return the SECOND result, not the first as (I) expected.
Use mysql_data_seek($res,0) to reset the result set.
adam dot chou at gmail dot com (2008-10-06 14:49:54)
mysql_result() will throw E_WARNING if mysql_query returns 0 rows. This is unlike any of the mysql_fetch_* functions so be careful of this if you have E_WARNING turned on in error_reporting(). You might want to check mysql_num_rows() before calling mysql_result()
kg6ypi at remotehams dot com (2008-05-01 17:54:33)
//updated error handling for mysql_evaluate
function mysql_evaluate($query, $default_value=0) {
if (!$result=mysql_query($query)) {
return 0;
}
if (mysql_num_rows($result)==0)
return $default_value;
else
return mysql_result($result,0);
}
// same applies for the mysql_evaluate_array() function
djurredenboer at hotmail dot com (2007-05-11 12:08:41)
<?
$link = mysql_connect("host", "user", "passw");
mysql_select_db("database", $link);
$number = 3;
$insert = mysql_query("SELECT `test1`.*, `test2`.*,
FROM `test1`, `test2`, `
WHERE ((`test1`.`author` = `test2`.`ID`) AND (`test2`.`ID` ='$number'))
ORDER BY `toetsen`.`autoID` DESC",$link);
echo mysql_result( $insert , 0, 'test1.question') ;
#here he echoes the questions the stuff out of the first table
echo mysql_result( $insert , 0, 'test2.name') ;
#here he echoes the questions the stuff out of the second table
?>
erelsgl dot NOSPAM at cs dot technion dot ac dot il (2006-09-12 04:18:22)
two simple but very useful functions, for converting a query to a value or an array:
<?php
function mysql_evaluate($query, $default_value="undefined") {
$result = mysql_query($query);
if (mysql_num_rows($result)==0)
return $default_value;
else
return mysql_result($result,0);
}
function mysql_evaluate_array($query) {
$result = mysql_query($query);
$values = array();
for ($i=0; $i<mysql_num_rows($result); ++$i)
array_push($values, mysql_result($result,$i));
return $values;
}
?>
http://tora.us.fm/_script/highlight.php?file=sql
Usage examples:
<?php
$customer_count = mysql_evaluate("SELECT COUNT(*) FROM customers");
$customer_names = mysql_evaluate_array("SELECT name FROM customers");
$customer_type = mysql_evaluate("SELECT type FROM customers WHERE name='$name'", "DEFAULT_TYPE");
?>
gack at bar dot foo (2006-07-18 07:42:24)
if you want to do something based on the fact that the data is the same in the next row, then looking ahead is easy with this.
<?php
$i=0;
$rows=mysql_num_rows($result);
while($i < $rows) {
$x = mysql_result($result, $i, 0);
if ($x = mysql_result($result, $i+1, 0)) {
echo "It's the same thing!";
}
}
?>
raz0 at NOSPAM dot worldonline dot dk (2003-08-23 10:42:47)
If you want to fetch the result from a mysql query similar to one of these two queries...
$query = mysql_query("SELECT COUNT(*) FROM table");
$query = mysql_query("SELECT LAST_INSERT_ID()");
... you would use mysql_result() like shown below to retrieve the output as an int.
$result = mysql_result($query, 0, 0);