我想問分組查詢是怎么在分組情況下把組內不同的id顯示出來的,完全不明白?
SELECT goods_id,goods_name FROM tdb_goods GROUP BY goods_name HAVING count(goods_name) >= 2;就這句,id18與21的name相同,19與22相同,按理說不應顯示id,應該報錯,我試驗也是報錯。但視頻中出id18,19,匪夷所思。
SELECT goods_id,goods_name FROM tdb_goods GROUP BY goods_name HAVING count(goods_name) >= 2;就這句,id18與21的name相同,19與22相同,按理說不應顯示id,應該報錯,我試驗也是報錯。但視頻中出id18,19,匪夷所思。
2018-04-27
舉報
2018-05-20
你這樣寫:SELECT goods_id,goods_name FROM tdb_goods GROUP BY goods_name HAVING count(goods_id) >= 2,通過name分組,看看哪個name對應了兩條ID,
2018-11-22
2018-10-29
為什么應該報錯啊,這是對的啊。GROUP BY分組以后每組不管有多少條記錄,都只顯示一條出來
2018-04-27
SELECT MIN(goods_id),goods_name FROM tdb_goods GROUP BY goods_name;這樣就成功了
自問自答