PHP PDO MSSQL ROW_NUMBER() error - php

Question

I'm using php pdo with SQL Server Native Client 11.0 as the driver.
Obiously I do cannot use LIMIT clause as it is proprietary and in trying to workarounf selecting ranges of rows I keep hitting issues.
My setup as follows :
$statement = "SELECT ROW_NUMBER() OVER (ORDER BY USERS.name DESC) AS RowNum, CASE.no, CASE.type, CASE.date, CASE.ju, USERS.name, TBRLMF.rd_rl_description FROM dbo.CASE INNER JOIN dbo.USERS ON dbo.CASE.no = dbo.USERS.case_no INNER JOIN dbo.CMSTBRLMF ON dbo.USERS.relationship = dbo.TBRLMF.code ";
if($exact == 'checked'){
$exact = '=';
}else{
$exact = 'LIKE';
}
if($searchtype == 'users'){
$statement .= " WHERE USERS.name $exact '%$searchstring%'";
}else{
$statement .= " WHERE USERS.no $exac '%$searchstring%'";
}
$statement .= " AND RowNum BETWEEN :offset AND :max";
$statement = $dbh->prepare($statement);
$statement->bindParam(':offset', $offset, PDO::PARAM_INT);
$statement->bindParam(':max', $max, PDO::PARAM_INT);
and as long as I do not include the line of code :
$statement .= " AND RowNum BETWEEN :offset AND :max";
It works fine but gives me all the data.
When that line is included I recieve the following error :-
caught exception 'PDOException' with message 'SQLSTATE[42S22]: Column not found: 207 [Microsoft][SQL Server Native Client 11.0][SQL Server]Invalid column name 'RowNum'. (SQLExecute[207] at ext\pdo_odbc\odbc_stmt.c:254)' in C:\pub\test\Classes\Core.php:44
I am at a loss and MSSQL is new to me.
Help much appreciated.

Answer 1

The predicate on that column can't be in a WHERE clause. (The predicates in the WHERE clause are evaluated when the rows are accessed; the value of that expression (analytic function) isn't available until after the rows are accessed.
You may be able to reference the column alias in a HAVING clause:
" HAVING RowNum BETWEEN ... ";

Answer 2

You can't use COLUMN ALIAS (RowNum in your case) in WHERE clause. Rather change your query using derived table like below
SELECT * FROM
(
SELECT ROW_NUMBER() OVER (ORDER BY USERS.name DESC) AS RowNum,
CASE.no,
CASE.type,
CASE.date,
CASE.ju,
USERS.name,
TBRLMF.rd_rl_description
FROM dbo.CASE
INNER JOIN dbo.USERS
ON dbo.CASE.no = dbo.USERS.case_no
INNER JOIN dbo.CMSTBRLMF
ON dbo.USERS.relationship = dbo.TBRLMF.code
WHERE USERS.name LIKE '%string%'
AND USERS.no LIKE '%string%'
) X
WHERE RowNum BETWEEN 1 AND 10;
EDIT:
You can also use CTE (Common Table Expression) to get around this like below
Create the CTE
WITH NEWCTE AS
(
SELECT ROW_NUMBER() OVER (ORDER BY USERS.name DESC) AS RowNum,
CASE.no,
CASE.type,
CASE.date,
CASE.ju,
USERS.name,
TBRLMF.rd_rl_description
FROM dbo.CASE
INNER JOIN dbo.USERS
ON dbo.CASE.no = dbo.USERS.case_no
INNER JOIN dbo.CMSTBRLMF
ON dbo.USERS.relationship = dbo.TBRLMF.code
WHERE USERS.name LIKE '%searchstring%'
AND USERS.no LIKE '%searchstring%'
)
Query the CTE
SELECT *
FROM NEWCTE
WHERE RowNum BETWEEN 1 AND 10