有条件的分组子句（sqlite） [英] Conditional grouping clause (sqlite)

问题描述

SELECT 语句中，如果 col_B = GROUP BY col_A some_value，否则 GROUP BY col_C ？然后让那个用于分组结果的字段？

像

  SELECT value_of_the_column_used_for_group 
 FROM table WHERE ... 
 GROUP BY（如果col_B =some_value：col_A：ELSE：col_C）
 LIMIT 0,20; 
  

基本上我想要选择具有不同父母或具有不同ID的父记录的子记录。但是我想选择父ID，它可以是ID列或儿童记录的parent_ID列。

你，你可以使用 case 语句：

  SELECT（col_B = 'some_value'then col_A ELSE col_C end）
 FROM table WHERE ... 
 GROUP BY（col_B ='some_value'时col_A ELSE col_C结束时）
 LIMIT 0,20; 
  

Inside a SELECT statement, is it possible to GROUP BY col_A if col_B = "some_value", otherwise GROUP BY col_C ? Then have that field that was used for grouping inside the results?

Like

SELECT value_of_the_column_used_for_group 
   FROM table WHERE ... 
   GROUP BY (IF col_B = "some_value" : col_A : ELSE : col_C)
   LIMIT 0, 20;

Basically I want to select children records that have distinct parents or parent records that have distinct IDs. But I want to select parent IDs, which can be the ID column or the "parent_ID" column from children records

解决方案

You, you can use a case statement:

SELECT (case when col_B = 'some_value' then col_A ELSE col_C end) 
FROM table WHERE ... 
GROUP BY (case when col_B = 'some_value' then col_A ELSE col_C end)
LIMIT 0, 20;

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