如何从mysql查询中只获取一行

i allways end up doing this

我总是最终这样做

$q = "select whatIwant FROM table where id = 'myId'";
$r = mysql_query($q);
while($i = mysql_fetch_array($r){
   /* iterate just one withem */
   $j = $i['whatIwant'];
}
echo $j;

how is this usually done? (i just want to avoid the unecessary loop)

这通常是怎么做的？（我只是想避免不必要的循环）

9 个解决方案

#1

In addition to the correct answers, there are multiple ways to handle this:

除了正确的答案，还有多种方法可以解决这个问题：

If you add LIMIT 1, the result set will only contain one row and the while loop will terminate after one iteration:

如果添加LIMIT 1，结果集将只包含一行，while循环将在一次迭代后终止：
```
$q = "select whatIwant FROM table where id = 'myId' LIMIT 1";
$r = mysql_query($q);
while($i = mysql_fetch_array($r)) {
   $j = $i['whatIwant'];
}
echo $j;
```
If you call mysql_fetch_array without a loop, you will get the first row of the result set:

如果在没有循环的情况下调用mysql_fetch_array，您将获得结果集的第一行：
```
$q = "select whatIwant FROM table where id = 'myId'";
$r = mysql_query($q);
$i = mysql_fetch_array($r);
$j = $i['whatIwant'];
echo $j;
```

If you add break to the loop body, the loop will terminate after one iteration.

如果向循环体添加break，则循环将在一次迭代后终止。

$q = "select whatIwant FROM table where id = 'myId'";
$r = mysql_query($q);
while($i = mysql_fetch_array($r)) {
   $j = $i['whatIwant'];
   break;
}
echo $j;

You can also combine these approaches (although using break is not really elegant in this case).

您也可以将这些方法结合起来（尽管在这种情况下使用break并不是很优雅）。

The best approach is using LIMIT and omitting the while loop, as @zaf shows in his answer. This makes the code clearer and avoids unnecessary operations in the database.

最好的方法是使用LIMIT并省略while循环，正如@zaf在他的回答中所示。这使代码更清晰，并避免了数据库中不必要的操作。

#2

You can specify the number of rows in the sql query using the 'LIMIT' syntax.

您可以使用“LIMIT”语法指定sql查询中的行数。

Also, you can just remove the while loop and get the first row returned - if thats all you want.

此外，您可以删除while循环并返回第一行 - 如果这就是您想要的全部内容。

For example (without returned value checking):

例如（没有返回值检查）：

$q = "select whatIwant FROM table where id = 'myId' LIMIT 1";
$r = mysql_query($q);
$i = mysql_fetch_array($r);
print_r($i);

#3

add LIMIT X, Y where X is your starting row and Y is the number of rows to return

添加LIMIT X，Y，其中X是您的起始行，Y是要返回的行数

//will always return 1 row. note your orders

$q = "SELECT whatIwant FROM table WHERE id = 'myId' limit 0, 1";

http://php.about.com/od/mysqlcommands/g/Limit_sql.htm

#4

select whatIwant FROM table where id = 'myId' limit 1

#5

Well then leave out the loop:

好吧然后省略循环：

$q = "select whatIwant FROM table where id = 'myId'";
$r = mysql_query($q);
$i = mysql_fetch_array($r);
$j = $i['whatIwant'];
echo $j;

This will only fetch the first line.

这只会获取第一行。

#6

mysql_fetch_assoc() is exactly what you're looking for.

mysql_fetch_assoc（）正是您正在寻找的。

http://php.net/mysqli_fetch_assoc

#7

I think you're looking for this:

我想你正在寻找这个：

http://php.net/manual/en/function.mysql-fetch-row.php

#8

select whatIwant FROM table where id = 'myId' LIMIT 1;

选择whatIwant FROM table，其中id ='myId'LIMIT 1;

http://dev.mysql.com/doc/refman/5.5/en/select.html

#9

$sql224="select * from z_category order by id asc LIMIT 1";
$res224=mysql_query($sql224);
$rw224=mysql_fetch_array($res224);
$activeid2= $rw224['pkid'];

#1