MySQL：如何合并多行以仅返回一行

Question

I have a sql table having multiple rows and i want to merge some of his rows to be in one row, if row columns different then return 'Mixed Value' else return the column value

Example:

I want the result to be like that if i select row with id 1 and 2

and if i select row with id 1,2 and 3

Thank's in advance

Answer 1

You could try using group_concat(distinct() )

SELECT GROUP_CONCAT(DISTINCT(firstname) SEPARATOR ' ') ,  
       GROUP_CONCAT(DISTINCT(lastname) SEPARATOR ' ')
FROM table

Answer 2

You can use a combination of CASE WHEN and COUNT(DISTINCT) to get what you want. It isn't clear if you want to group by price_id or by service_id , but I will assume so.

SELECT MIN(id) id, 
CASE WHEN COUNT(DISTINCT firstname) > 1 THEN 'MIXED_VALUE' ELSE MIN(firstname) END firstname,
CASE WHEN COUNT(DISTINCT lastname) > 1 THEN 'MIXED_VALUE' ELSE MIN(lastname) END lastname,
price_id, service_id,
CASE WHEN COUNT(DISTINCT product_sku) > 1 THEN 'MIXED_VALUE' ELSE MIN(product_sku) END product_sku
FROM yourTable
GROUP BY price_id, service_id