MySql If else 条件

Question

是否有可能为给定的 mysql 查询引入 if else？此查询生成 4 列。这可以放在一个列中吗？

SELECT 
    IF(regression.execution_date >= CONCAT(YEAR(CURDATE() - 1), '-','07', '-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '09', '-', '30'), CONCAT(YEAR(CURDATE() - 1), '.', '1'), 0) AS 'Q1',
    IF(regression.execution_date >= CONCAT(YEAR(CURDATE() - 1),'-','10','-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '12', '-', '31'), CONCAT(YEAR(CURDATE() - 1), '.', '2'),0) AS 'Q2',
    IF(regression.execution_date >= CONCAT(YEAR(CURDATE()), '-', '01', '-', '01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '03', '-', '31'), CONCAT(YEAR(CURDATE()), '.', '3'), 0) AS 'Q3',
    IF(regression.execution_date >= CONCAT(YEAR(CURDATE()), '-', '04', '-', '01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '06', '-', '31'), CONCAT(YEAR(CURDATE()), '.', '4'), 0) AS 'Q4'
FROM
    regression

解决方法:

感谢大家的评论。我用 case 实现了它，它起作用了。

SELECT 
CASE 
WHEN regression.execution_date >= CONCAT(YEAR(CURDATE() - 1), '-','07', '-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '09', '-', '30') THEN (CONCAT(YEAR(CURDATE() - 1), '.', '1')) 
WHEN regression.execution_date >= CONCAT(YEAR(CURDATE() - 1), '-','10', '-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '12', '-', '31') THEN (CONCAT(YEAR(CURDATE() - 1), '.', '2')) 
WHEN regression.execution_date >= CONCAT(YEAR(CURDATE()), '-','01', '-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '03', '-', '31') THEN (CONCAT(YEAR(CURDATE()), '.', '3')) 
WHEN regression.execution_date >= CONCAT(YEAR(CURDATE()), '-','04', '-','01') AND regression.execution_date <= CONCAT(YEAR(CURDATE()), '-', '06', '-', '31') THEN (CONCAT(YEAR(CURDATE()), '.', '4')) 
END as 'Quarter'
FROM 
regression

Answer 1

要计算实际的四分之一吗？

使用这个:

SELECT QUARTER(now());

样本

MariaDB [(none)]> SELECT  QUARTER(now());
+----------------+
| QUARTER(now()) |
+----------------+
|              2 |
+----------------+
1 row in set (0.00 sec)

MariaDB [(none)]> SELECT  QUARTER('2015-10_07');
+-----------------------+
| QUARTER('2015-10_07') |
+-----------------------+
|                     4 |
+-----------------------+
1 row in set (0.00 sec)

MariaDB [(none)]>