Question

我在SELECT中有CASE条件。以下是查询条件

查询来自视图

SELECT expt_id,stain_type,control_stain, test_stain
   CASE WHEN stain_type = 'Blue' THEN control_stain = 'NA'
   CASE WHEN stain_type = 'Hemat' THEN test_stain = 'NA'
FROM experiment_results__view

这里的值是＆＃39; NA＆＃39;必须填充stain_type的条件。非常感谢您提供有关如何撰写此查询的建议

谢谢！

Answer 1

我希望您能够使用该行中的内容：

SELECT 
   expt_id,
   stain_type,
   CASE WHEN stain_type = 'Blue' THEN 'NA' ELSE NULL END control_stain, 
   CASE WHEN stain_type = 'Hemat' THEN 'NA' ELSE NULL END test_stain
FROM experiment_results__view

获取你的价值＆＃39; NA＆＃39;到名为control_stain和test_stain的列中。但是，如果您想要覆盖这些列中的现有值，并使用值＆＃39; NA＆＃39;在这些情况下，然后使用：

SELECT 
   expt_id,
   stain_type,
   CASE WHEN stain_type = 'Blue' THEN 'NA' ELSE control_stain END control_stain, 
   CASE WHEN stain_type = 'Hemat' THEN 'NA' ELSE test_stain END test_stain
FROM experiment_results__view

如果您打算更新表格，那么您应该将其重写为：

UPDATE 
   experiment_results__view 
SET 
   control_stain = CASE WHEN stain_type = 'Blue' THEN 'NA' ELSE control_stain END, 
   test_stain = CASE WHEN stain_type = 'Hemat' THEN 'NA' ELSE test_stain END
-- if you don't want to update the complete table add an WHERE clause
WHERE
   <some condition>

Answer 2

你需要END每个案例陈述

SELECT expt_id,stain_type,
   CASE WHEN stain_type = 'Blue' THEN 'NA' ELSE control_stain END AS 'Control Stain'
   CASE WHEN stain_type = 'Hemat' THEN 'NA' ELSE test_stain END AS 'Test Stain'
FROM experiment_results__view

如果您打算更新表格，可以进行更新查询

UPDATE 
    experiment_results__view
SET 
    control_stain = CASE WHEN stain_type = 'Blue'  THEN 'NA' ELSE control_stain END,
    test_stain    = CASE WHEN stain_type = 'Hemat' THEN 'NA' ELSE test_stain END

MySQL中SELECT语句中的CASE条件

2 个答案: