从数据库获取下一个表行的特定列元素

Question

I have a query which selects userid,messageid,statusid from tableA like following.

$qry = mssql_query('select userid,messageid,statusid from tableA');
if(mssql_num_rows($qry))
{
   $data = mssql_fetch_array($qry)
   {
     //if(current_status_id column value != next_status_id column value)
     $status = $data['statusid'];
   }
}

I need to compare the value of current statusid column with the immediate next row statusid column like this if(current_status_id column value != next_status_id column value) .Is this possible.Pls help me

Answer 1

$qry = mssql_query('select userid,messageid,statusid from tableA order by statusid');
while (($row=mssql_fetch_array($qry) !== FALSE) {
    if (isset($previous) && $previous['statusid'] !== $row['statusid']) {
        // do what you gotta do here
    }
    $previous = $row;
}

I added order by statusid to your SQL so that you do get an order set of data. And rather than trying to "look ahead" to the next row, the code above "looks back" to the previous row ... which is effectively the same. You've got the data of the two rows in $previous and $row so you should be able to do what you wanna do with $previous .

Answer 2

I have created an array and assigned the results into it.Then I used while loop and checked if the current element is not equal to next element.

$i=1;
while (($row = mssql_fetch_array($qry, MYSQL_ASSOC)) !== false)
{
     $data_array[] = $row; // add the row in to the results (data) array
} 
mssql_data_seek( $qry, 0 );
while($msgDetailChilds = mssql_fetch_array($qry)){ 
   if($data_array[$i]['groupid']!=$data_array[$i-1]['groupid'])
   {
      //do stuff
   }

}