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SQL: Join vs. subquery
Is there anything that we can do with joins but not with subqueries or vice-versa?
在大多数企业申请中,它不仅是一个可做的事,而且还可以做。 一般来说,儒昂比按次年价要快,费用要低。 在SO方面担任其他职务。 http://stackoverflow.com/questions/2577174/sql-join-vs-subquery”
坦率地说,我想到的是,从两种方法(顺序或加入)中可以得出一点。
对我来说,这更多地涉及可读性和业绩。 例如,分局可能较慢,而合并可能会利用某些指数。 至少从房舍管理司的角度来看,我想,在分析这一表述时,应更容易优化加入。
举例来说,考虑几个加入国的情况。 对大多数人来说,如果将发言视为<代码>Left,Rights/code>或 vs Inner加入,便更容易理解和维护。 我甚至避免使用暗中加入,因为它们掩盖了意图。 换言之,我更愿意作为<条码>表示加入,从表格中填入表b, id=b.id,从表a. b.id=b.id.。 海事组织作为分局实施合并,使之更不易读。
$db_user="root"; $db_host="localhost"; $db_password="root"; $db_name = "fayer"; $conn = mysqli_connect($db_host,$db_user,$db_password,$db_name) or die ("couldn t connect to server"); // perform query ...
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Is it because of size? By the way, what is the limit of the size?
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