SQL来查找列中不同值的数量

我可以通过以下方式选择一列中所有不同的值:

SELECT DISTINCT column_name FROM table_name SELECT column_name FROM table_name

但是如何从该查询中获得行数呢?是否需要子查询?

当前回答

select Count(distinct columnName) as columnNameCount from tableName

其他回答

在MS SQL Server 2012之后，你也可以使用窗口函数。

SELECT column_name, COUNT(column_name) OVER (PARTITION BY column_name) 
FROM table_name
GROUP BY column_name

column_name的唯一值的sql和，并按频率排序:

SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name ORDER BY 2 DESC;

select Count(distinct columnName) as columnNameCount from tableName

你可以在COUNT聚合函数中使用DISTINCT关键字:

SELECT COUNT(DISTINCT column_name) AS some_alias FROM table_name

这将只计算该列的不同值。

select count(*) from 
(
SELECT distinct column1,column2,column3,column4 FROM abcd
) T

这将给出不同列组的计数。

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