87 lines
4.9 KiB
PHP
87 lines
4.9 KiB
PHP
<?php
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$str = "
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The following examples should give a hint of how DQL is converted into SQL.
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The classes used in here are the same as in chapter 14.1 (Users and groups are both entities etc).
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DQL QUERY: FROM Email WHERE Email.address LIKE '%@example%'
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SQL QUERY: SELECT email.id AS Email__id FROM email WHERE (email.address LIKE '%@example%')
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DQL QUERY: FROM User(id) WHERE User.Phonenumber.phonenumber LIKE '%123%'
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SQL QUERY: SELECT entity.id AS entity__id FROM entity LEFT JOIN phonenumber ON entity.id = phonenumber.entity_id WHERE phonenumber.phonenumber LIKE '%123%' AND (entity.type = 0)
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DQL QUERY: FROM Forum_Board(id).Threads(id).Entries(id)
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SQL QUERY: SELECT forum_board.id AS forum_board__id, forum_thread.id AS forum_thread__id, forum_entry.id AS forum_entry__id FROM forum_board LEFT JOIN forum_thread ON forum_board.id = forum_thread.board_id LEFT JOIN forum_entry ON forum_thread.id = forum_entry.thread_id
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DQL QUERY: FROM User(id) WHERE User.Group.name = 'Action Actors'
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SQL QUERY: SELECT entity.id AS entity__id FROM entity LEFT JOIN groupuser ON entity.id = groupuser.user_id LEFT JOIN entity AS entity2 ON entity2.id = groupuser.group_id WHERE entity2.name = 'Action Actors' AND (entity.type = 0 AND (entity2.type = 1 OR entity2.type IS NULL))
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DQL QUERY: FROM User(id) WHERE User.Group.Phonenumber.phonenumber LIKE '123 123'
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SQL QUERY: SELECT entity.id AS entity__id FROM entity LEFT JOIN groupuser ON entity.id = groupuser.user_id LEFT JOIN entity AS entity2 ON entity2.id = groupuser.group_id LEFT JOIN phonenumber ON entity2.id = phonenumber.entity_id WHERE phonenumber.phonenumber LIKE '123 123' AND (entity.type = 0 AND (entity2.type = 1 OR entity2.type IS NULL))
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";
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function renderQueries($str) {
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$e = explode("\n",$str);
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$color = "367FAC";
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foreach($e as $line) {
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if(strpos($line, "SQL") !== false)
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$color = "A50A3D";
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elseif(strpos($line, "DQL") !== false)
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$color = "367FAC";
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$l = str_replace("SELECT","<br \><font color='$color'><b>SELECT</b></font>",$line);
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$l = str_replace("FROM","<br \><font color='$color'><b>FROM</b></font>",$l);
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$l = str_replace("LEFT JOIN","<br \><font color='$color'><b>LEFT JOIN</b></font>",$l);
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$l = str_replace("INNER JOIN","<br \><font color='$color'><b>INNER JOIN</b></font>",$l);
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$l = str_replace("WHERE","<br \><font color='$color'><b>WHERE</b></font>",$l);
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$l = str_replace("AS","<font color='$color'><b>AS</b></font>",$l);
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$l = str_replace("ON","<font color='$color'><b>ON</b></font>",$l);
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$l = str_replace("ORDER BY","<font color='$color'><b>ORDER BY</b></font>",$l);
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$l = str_replace("LIMIT","<font color='$color'><b>LIMIT</b></font>",$l);
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$l = str_replace("OFFSET","<font color='$color'><b>OFFSET</b></font>",$l);
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$l = str_replace("DISTINCT","<font color='$color'><b>DISTINCT</b></font>",$l);
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$l = str_replace(" ","<dd>",$l);
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print $l."<br>";
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if(substr($l,0,3) == "SQL") print "<hr valign='left' class='small'>";
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}
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}
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renderQueries($str);
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?>
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Propably the most complex feature DQL parser has to offer is its LIMIT clause parser. In pure
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sql the limit clause limits the number of rows returned. So for example when fetching users and their
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phonenumbers using limit 20 you might get anything between 1-20 users, since the first user might have 20 phonenumbers and
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hence the record set would consist of 20 rows.
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<br \><br \>
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DQL overcomes this problem with subqueries and with complex but efficient subquery analysis. In the next example
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we are going to fetch first 20 users and all their phonenumbers with single efficient query. Notice how the DQL parser is smart enough
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to use column aggregation inheritance even in the subquery.
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<br \><br \>
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<?php
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$str = "
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DQL QUERY: FROM User(id).Phonenumber LIMIT 20
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SQL QUERY: SELECT entity.id AS entity__id, phonenumber.id AS phonenumber__id, phonenumber.phonenumber AS phonenumber__phonenumber, phonenumber.entity_id AS phonenumber__entity_id FROM entity LEFT JOIN phonenumber ON entity.id = phonenumber.entity_id WHERE entity.id IN (SELECT DISTINCT entity.id FROM entity WHERE (entity.type = 0) LIMIT 20) AND (entity.type = 0)
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";
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renderQueries($str);
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?>
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In the next example
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we are going to fetch first 20 users and all their phonenumbers and only those users that actually have phonenumbers (hence the usage of colon operator = INNER JOIN) with single efficient query.
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Notice how the DQL parser is smart enough to use the INNER JOIN in the subquery.
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<br \>
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<?php
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$str = "
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DQL QUERY: FROM User(id):Phonenumber LIMIT 20
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SQL QUERY: SELECT entity.id AS entity__id, phonenumber.id AS phonenumber__id, phonenumber.phonenumber AS phonenumber__phonenumber, phonenumber.entity_id AS phonenumber__entity_id FROM entity INNER JOIN phonenumber ON entity.id = phonenumber.entity_id WHERE entity.id IN (SELECT DISTINCT entity.id FROM entity INNER JOIN phonenumber ON entity.id = phonenumber.entity_id WHERE (entity.type = 0) LIMIT 20) AND (entity.type = 0)
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";
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renderQueries($str);
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?>
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