将多行组合成一行，包含多列

Question

你好我要用字段x选择和分组，但在一行显示几列

SELECT * FROM `cityname` 
WHERE `city`='mashhad' 
group by `city`,`number` 
ORDER BY `city`

但我想要展示：

mashhad  935 915 937 901 

Answer 1

由于您希望每个number中的所有city，并在分隔列中显示所有数字，这将是表格轴问题，请尝试以下查询：

SELECT city, 
       MAX(CASE WHEN number = 935 THEN number ELSE NULL END) AS number_935, 
       MAX(CASE WHEN number = 915 THEN number ELSE NULL END) AS number_915, 
       MAX(CASE WHEN number = 937 THEN number ELSE NULL END) AS number_937, 
       MAX(CASE WHEN number = 901 THEN number ELSE NULL END) AS number_901 
FROM   cityname 
GROUP  BY city 

Demo Here