mysql同一个字段，多条记录拼接成一条

拼接前查询结果：

SQL语句：其中plate_essential是中间表

SELECT a.*, c.plate FROM stock_essential_data a 
LEFT JOIN plate_essential b ON a.id = b.essential_id
LEFT JOIN stock_plate c ON b.plate_id = c.id

使用GROUP_CONCAT函数按字段拼接结果

SELECT a.*,GROUP_CONCAT(c.plate separator'|') plate FROM stock_essential_data a
LEFT JOIN plate_essential b ON a.id = b.essential_id
LEFT JOIN stock_plate c ON b.plate_id = c.id
group by a.id

还能使用separator指定拼接符：GROUP_CONCAT(c.plate separator'|')

SELECT a.*,GROUP_CONCAT(c.plate separator'|') plate FROM stock_essential_data a
LEFT JOIN plate_essential b ON a.id = b.essential_id
LEFT JOIN stock_plate c ON b.plate_id = c.id
group by a.id