sql count() over() 和distinct 怎么共用

可以使用以下语法将 COUNT() OVER() 和 DISTINCT 结合起来使用：

SELECT COUNT(DISTINCT column_name) OVER() FROM table_name;

这将返回表中唯一值的数量。请注意，这将计算表中所有行的唯一值数量，而不是基于其他聚合函数的结果。如果您需要基于其他聚合函数计算唯一值数量，可以将它们包含在子查询中，然后将结果与 COUNT(DISTINCT column_name) OVER() 结合使用。

相关问题

sql count distinct

在SQL中，使用COUNT(DISTINCT 列名)可以统计某个列中不重复的唯一值的数量。例如，对于表格fromtable，可以使用以下查询语句统计userType为1和2的不重复userid的数量:

SELECT COUNT(DISTINCT case when userType=1 then userid else null end) as 类型1, COUNT(DISTINCT case when userType=2 then userid else null end) as 类型2 FROM fromtable

这个查询语句会返回两个列，分别是类型1和类型2对应的不重复userid的数量。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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sql count(distinct)

The SQL COUNT(DISTINCT) function is used to count the number of unique/distinct values in a column of a table. It takes the following syntax:

SELECT COUNT(DISTINCT column_name) FROM table_name;

For example, if we have a table named "students" with columns "id", "name", and "age", and we want to count the number of unique ages in the table, we would use the following SQL query:

SELECT COUNT(DISTINCT age) FROM students;

This would return the number of distinct ages in the "students" table.