SQLite计数，按计数分组和排序 [英] SQLite count, group and order by count

问题描述

我有一个看起来像这样的表:

I have a table that looks like this:

FOO  BAR  BAZ
----+----+----
foo1 bar1 baz1
foo2 bar3 baz2
foo3 bar1 baz3
foo4 bar1 baz4
foo5 bar3 baz5
foo6 bar1 baz6
foo7 bar2 baz7

因此，我想获得每个小节出现在表格中的次数..因此，我正在寻找的输出看起来像这样:

And as a result I would like to get the count of how many times each bar appeared in the table.. so, the output I'm looking for looks like this:

BAR   COUNT
-----+-----
bar1    4
bar3    2
bar2    1

我可以在SQLite中查询类似的内容吗?我想这应该很简单，但是无论如何我都不是SQL程序员，我只需要将此简单查询作为python脚本的一部分即可.谢谢.

Can I do a query for something like this in SQLite? I guess it should be pretty easy, but I am not an SQL programmer by any means, and I just need this simple query as a part of a python script.. Thank you.

推荐答案

SELECT foo, count(bar) FROM mytable GROUP BY bar ORDER BY count(bar) DESC;

group by语句告诉聚合函数按列对结果集进行分组.在这种情况下，按栏分组"表示按栏的不同类型"对栏列中的字段数进行计数.

The group by statement tells aggregate functions to group the result set by a column. In this case "group by bar" says count the number of fields in the bar column, grouped by the different "types" of bar.

更好的解释在这里: http://www.w3schools.com/sql/sql_groupby.asp

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