Question

我正在寻找一种方法来查询：

MySQL的：

示例：IF SELECT COUNT(column_XX) WHERE column_XX = value_XX FROM table_XX大于零（0）然后SELECT所有内容或SELECT * FROM table_XX WHERE column_XX = value_XX和返回所有数据......否则返回＆＃39;找不到任何内容＆＃39; 或只是ZERO（0）< / p>

简单来说，如果列中的所有值都大于零，我想从表列中选择所有数据，否则只选择值＆gt; = 1并返回所有值。

在单一查询中可以应用哪个魔术？...我真的非常感谢。

Answer 1

你可以尝试这样：

SELECT * FROM table_XX
WHERE column_XX = (
  SELECT column_XX FROM table_XX 
  WHERE column_XX = value_XX GROUP BY column_XX HAVING COUNT(column_XX) > 0
)

Answer 2

这会有用吗？

SELECT * FROM test_enum;
+------+-------+----------+
| ID   | Name  | IsActive |
+------+-------+----------+
|    1 | Abdul | No       |
|    1 | Abdul | Yes      |
+------+-------+----------+
2 rows in set (0.00 sec)

SELECT * FROM test_enum WHERE EXISTS(SELECT * FROM test_enum WHERE IsActive = 'No') AND IsActive = 'No';
+------+-------+----------+
| ID   | Name  | IsActive |
+------+-------+----------+
|    1 | Abdul | No       |
+------+-------+----------+
1 row in set (0.00 sec)

MYSQL IF SELECT COUNT（）大于零select select * from table else返回任何未找到的内容

2 个答案: