统计记录数目：函数COUNT（）也许是最有用的集合函数。 1．你可以用这个函数来统计一个表中有多少条记录。 SELECT COUNT(au_lname) FROM authors 这个例子计算表authors中名字（last name）的数目。如果相同的名字出现了不止一次，该名字将会被计算多次。 2．如果你想知道名字为某个特定值的作者有多少个，你可以使用WHERE子句，如下例所示： SELECT COUNT(au_lname) FROM authors WHERE au_lname=’Ring
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对于地球科学专业的学者来说，此教程有很好的指导作用，能够帮助快速上手，快速了解matlab在地学当中的用途和操作方法。Martin h. trauth
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