Question

假设我有四个表，我必须只选择 3 表，其数据库名为记录

Records
1.Cases
2.Ballistics
3.Chem
4.Accounts

Cases
id|year|Natureofcase |
0 |    |Repact 1901a |
1 |2003|Repact 1907b |
3 |2004|Repact 1902  |

Ballistics
id|year|Name     |Type  |
0 |2003|         |a-101 | 
1 |    |Silver-A |a-202 |
3 |2005|Red Cap  |      |

Chem
id|year|Identified   |
0 |    |H20+C20      |
1 |2001|Am           |
3 |2009|             |

所以我们有 6 行和空表。我希望使用PHP显示总和 6 。谢谢。任何意见/答案/建议将受到高度赞赏。

Answer 1

请试试这个

SELECT 
   (SELECT COUNT(*) FROM Cases WHERE year = '' OR Natureofcase = '') +
   (SELECT COUNT(*) FROM Ballistics WHERE year ='' OR Name='' OR Type='') +
   (SELECT COUNT(*) FROM Chem WHERE year='' OR Identified='')
AS total_empty

如何使用空字段计算所选表中的所有记录

1 个答案: