作者:苏木影子Hc_657 | 来源:互联网 | 2023-10-11 10:06
count计算不重复的记录SELECTCOUNT(DISTINCTplayer_id)FROMtask;返回记录不同的idSELECTDISTINCTplayer_idFROMta
count计算不重复的记录
SELECT COUNT( DISTINCT player_id ) FROM task;
返回记录不同的id
SELECT DISTINCT player_id FROM task;
同时作用于两列
SELECT DISTINCT player_id, task_id FROM task;