Doctrine\DBAL\Platforms\SQLServerPlatform::doModifyLimitQuery()

Complexity

Conditions	6
Paths	16

Size

Total Lines	44
Code Lines	23

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	18
CRAP Score	6.0052

Importance

Changes

0

<?php
    protected function doModifyLimitQuery(string $query, ?int $limit, int $offset) : string
    {
        $where = [];

        if ($offset > 0) {
            $where[] = sprintf('doctrine_rownum >= %d', $offset + 1);
        }

        if ($limit !== null) {
            $where[] = sprintf('doctrine_rownum <= %d', $offset + $limit);
            $top     = sprintf('TOP %d', $offset + $limit);
        } else {
            $top = 'TOP 9223372036854775807';
        }

        if (empty($where)) {
            return $query;
        }

        // We'll find a SELECT or SELECT distinct and prepend TOP n to it
        // Even if the TOP n is very large, the use of a CTE will
        // allow the SQL Server query planner to optimize it so it doesn't
        // actually scan the entire range covered by the TOP clause.
        if (! preg_match('/^(\s*SELECT\s+(?:DISTINCT\s+)?)(.*)$/is', $query, $matches)) {
            return $query;
        }

        $query = $matches[1] . $top . ' ' . $matches[2];

        if (stristr($query, 'ORDER BY')) {
            // Inner order by is not valid in SQL Server for our purposes
            // unless it's in a TOP N subquery.
            $query = $this->scrubInnerOrderBy($query);
        }

        // Build a new limited query around the original, using a CTE
        return sprintf(
            'WITH dctrn_cte AS (%s) '
            . 'SELECT * FROM ('
            . 'SELECT *, ROW_NUMBER() OVER (ORDER BY (SELECT 0)) AS doctrine_rownum FROM dctrn_cte'
            . ') AS doctrine_tbl '
            . 'WHERE %s ORDER BY doctrine_rownum ASC',
            $query,
            implode(' AND ', $where)
        );