如何计算两列中具有相同值的行，并仅返回count计数的行

Question

关于这个问题： How to count rows that have the same values in two columns (SQL)?

有没有办法只返回计数为＆lt;的行。 3？

+-----+-----+-----+
|  A  |  B  |count|
+=====+=====+=====+
|  1  |  3  |  2  |
+-----+-----+-----+
|  4  |  2  |  1  |
+-----+-----+-----+

Answer 1

HAVING子句

 SELECT ...
 FROM ...
 WHERE ...
 GROUP BY whatever
 HAVING count(*) <3

Answer 2

只需在HAVING子句中添加条件

即可

SELECT colName, COUNT(*)
FROM tableName
GROUP BY colName
HAVING COUNT(*) < 3