我们已知某张表的type的取值是1，2，3，4，5，想要统计不同type的数据量，并清晰的展现出来。可以通过union all 的方式，sql如下：
SELECT "1",COUNT(*) FROM table_name WHERE type = "1" UNION ALL SELECT "2",COUNT(*) FROM table_name WHERE type = "2" UNION ALL SELECT "3",COUNT(*) FROM table_name WHERE type = "3" UNION ALL SELECT "4",COUNT(*) FROM table_name WHERE type = "4" UNION ALL SELECT "5",COUNT(*) FROM table_name WHERE type = "5"
得到的结果如下：
| type | count(*) |
| 1 | 324 |
| 2 | 123 |
| 3 | 345 |
| 4 | 156 |
| 5 | 343 |
原文：https://www.cnblogs.com/drjava/p/10479705.html