我有下表,我想在MySQL 5.7中使用group_concat函数,但显示错误。谁能帮我吗?
**ride** **route**
r_id Date region route_name r_id
1 2019-09-11 DXB dx1 1
2 2019-09-11 AUH au1 2
3 2019-09-11 DXB dx2 3
4 2019-09-11 NE ne1 4
我正在对group_concat使用以下查询,但显示错误
SELECT region,GROUP_CONCAT(route_name) AS route_name FROM route LEFT JOIN ride ON r_id = r_id WHERE service_date = '2019-11-05' GROUP BY region
join的ON
子句存在语法问题。您在查询中使用别名是正确的,但这是一个可能有效的版本:
SELECT
ro.region,
GROUP_CONCAT(ri.route_name) AS route_name
FROM route ro
LEFT JOIN ride ri
ON ri.r_id = ro.r_id
WHERE
ri.service_date = '2019-11-05'
GROUP BY
ro.region;