显示mysqli查询的单列值

Question

How can I get a single column value from mysqli? The result should be single row with only one column.

This is what I have tried:

$query = "SELECT MAX(`userid`) FROM `user`";
$rlt = mysqli_query($this->db, $query);
echo $rlt['userid'];

Answer 1

You are not fetching the row after executing the query:

$query = "SELECT MAX(`userid`) FROM `user'";
$rlt = mysqli_query($this->db,$query);
$row = mysqli_fetch_row($this->db, $rlt);
echo $row[0];

The alternative would be to use an alias for the computed field and use fetch_assoc :

$query = "SELECT MAX(`userid`) as `maxid` FROM `user'";
$rlt = mysqli_query($this->db,$query);
$row = mysqli_fetch_assoc($this->db, $rlt);
echo $row['maxid'];

Answer 2

try with create alias and fetch result after query execution also your quote of user' looking wrong

$query = "SELECT MAX(`userid`) as userid  FROM `user`";
$rlt = mysqli_query($this->db,$query);
$r = mysqli_fetch_assoc($rlt);
echo $r['userid'];

or fetch only one row like:-

$r = mysqli_fetch_row($this->db, $rlt);
echo $r[0];

Answer 3

You should create alias here.

Use this one:

$query = "SELECT MAX(`userid`) as Max_Userid  FROM `user'";
$rlt = mysqli_query($this->db,$query);
$row = mysqli_fetch_assoc($this->db, $rlt);
echo $row['Max_Userid'];

Note: Always use alias when you use mysql function in query with fields.