一、函式語法：

　　group_concat( [DISTINCT] 要連線的欄位 [Order BY 排序欄位 ASC/DESC] [Separator ‘分隔符’] )

　　下面舉例說明：select id,price from goods;

　　以id分組，把price欄位的值在同一行打印出來，逗號分隔(預設)：select id, group_concat(price) from goods group by id;

　　以id分組，把price欄位的值在一行打印出來，分號分隔：select id,group_concat(price separator ';') from goods group by id;

　　以id分組，把去除重複冗餘的price欄位的值列印在一行，逗號分隔：select id,group_concat(distinct price) from goods group by id;

　　以id分組，把price欄位的值去重列印在一行，逗號分隔，按照price倒序排列：select id,group_concat(DISTINCT price order by price desc) from goods group by id;