Question

是否有可能为给定的mysql查询引入if else？此查询产生4列。这可以在一个列中吗？

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

解决方案：

感谢大家的评论。我用case实现了它。它有用。

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

你想计算实际的季度吗？

使用它：

major

<强>样品

SELECT QUARTER(now());

Answer 2

只需将您的日期改为7个月即可获得您想要的自定义区域：

SELECT(QUARTER(DATE_SUB(execution_date, INTERVAL 7 MONTH)))
FROM regression

如果您想使用原始方法，请继续阅读。我在查询中看到了几个问题/效率低下，我试图纠正。首先，因为您的查询位于regression表上，所以在选择列时不需要显式引用此表，因此我不再使用它。其次，您试图将execution_date（可能是日期类型）与字符串进行比较，字符串是CONCAT()输出的类型。所以我使用STR_TO_DATE()将手工建立的日期字符串转换为实际的日期类型。最后，我用一个IF表达式替换了一组噩梦般的嵌套CASE语句。

CASE WHEN execution_date >= STR_TO_DATE(CONCAT(YEAR(CURDATE() - 1), '-', '07', '-', '01'), '%Y-%m-%d') AND
          execution_date <= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '09', '-', '30'), '%Y-%m-%d')
     THEN CONCAT(YEAR(CURDATE() - 1), '.', '1')
     WHEN execution_date >= STR_TO_DATE(CONCAT(YEAR(CURDATE() - 1), '-', '10', '-', '01'), '%Y-%m-%d') AND
          execution_date <= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '12', '-', '31'),'%Y-%m-%d')
     THEN CONCAT(YEAR(CURDATE() - 1), '.', '2')
     WHEN execution_date >= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '01', '-', '01'), '%Y-%m-%d') AND
          execution_date <= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '03', '-', '31'), '%Y-%m-%d')
     THEN CONCAT(YEAR(CURDATE()), '.', '3')
     WHEN execution_date >= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '04', '-', '01'), '%Y-%m-%d') AND
          execution_date <= STR_TO_DATE(CONCAT(YEAR(CURDATE()), '-', '06', '-', '31'), '%Y-%m-%d')
     THEN CONCAT(YEAR(CURDATE()), '.', '4')
     ELSE '0' END AS theQuarter
FROM regression

MySql If else条件

2 个答案: