MySQL之group_concat 配合substring_index查詢

字符串鏈接：group_concat([DISTINCT] 要鏈接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符'])

字符串截取：substring_index(str,delim,count)

例如查詢每一個用戶的最大投資額：

select investoruserid,substring_index(group_concat(investamount order by investamount desc separator ','),',',1) from loan_investor group by investoruserid;