db

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<?php
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namespace Upside\Db\SQL\Compiler;
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use Upside\Db\SQL\Compiler;
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use Upside\Db\SQL\SQLStatement;
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class DB2 extends Compiler
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{
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    /**
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     * Returns the SQL for a select statement
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     */
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    public function select(SQLStatement $select): string
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    {
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        $limit = $select->get_limit();
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        if ($limit <= 0) {
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            return parent::select($select);
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        }
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        $order = \trim($this->handle_orderings($select->get_order()));
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        if (empty($order)) {
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            $order = 'ORDER BY (SELECT 0)';
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        }
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        $sql = $select->get_distinct() ? 'SELECT DISTINCT ' : 'SELECT ';
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        $sql .= $this->handle_columns($select->get_columns());
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        $sql .= ', ROW_NUMBER() OVER (' . $order . ') AS opis_rownum';
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        $sql .= ' FROM ';
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        $sql .= $this->handle_tables($select->get_tables());
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        $sql .= $this->handle_joins($select->get_joins());
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        $sql .= $this->handle_wheres($select->get_wheres());
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        $sql .= $this->handle_groupings($select->get_group_by());
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        $sql .= $this->handle_havings($select->get_having());
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        $offset = $select->get_offset();
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        if ($offset < 0) {
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            $offset = 0;
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        }
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        $limit += $offset;
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        $offset++;
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        return 'SELECT * FROM (' . $sql . ') AS m1 WHERE opis_rownum BETWEEN ' . $offset . ' AND ' . $limit; // TODO: opis_rownum
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    }
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}
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