Mysql 如何对两列中具有相同值的行进行计数，并仅返回count<；N（SQL）？

关于这个问题：

是否有方法仅返回计数小于3的行

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

---

具有子句的

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

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

选择。。。
从…起
哪里
按什么分组
HAVING count（*）只需在
HAVING
子句中添加条件

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

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

选择colName，COUNT（*）
从表名
按colName分组
计数（*）小于3的