mysql - 使用 where 子句左连接三个表

Question

谁能告诉我这个查询有什么错误错误:ER_PARSE_ERROR:你的 SQL 语法有错误；检查与您的 MySQL 服务器版本对应的手册，了解在“LEFT JOIN where YEAR at line 1”附近使用的正确语法

SELECT uw.user_id, cd.LEW, cd.event_date,dd.hwRate,d3.Wdata
FROM user_worker AS uw
LEFT JOIN _device1 AS cd ON uw.user_id = cd.uuid     
WHERE YEAR(cd.event_date)=2018 
LEFT JOIN _device2 AS dd ON uw.user_id = dd.uuid 
WHERE YEAR(dd.event_date)=2018 
LEFT JOIN _device3 AS d3 ON uw.user_id = d3.uuid 
WHERE YEAR(d3.event_date)=2018 

Answer 1

如评论中所述，每个连接不能有多个位置，但如果用“AND”替换所有位置，它将起作用:

SELECT uw.user_id, cd.LEW, cd.event_date,dd.hwRate,d3.Wdata
FROM user_worker AS uw
LEFT JOIN _device1 AS cd ON uw.user_id = cd.uuid     
 AND YEAR(cd.event_date)=2018 
LEFT JOIN _device2 AS dd ON uw.user_id = dd.uuid 
 AND YEAR(dd.event_date)=2018 
LEFT JOIN _device3 AS d3 ON uw.user_id = d3.uuid 
 AND  YEAR(d3.event_date)=2018