count_distinct3.result

来自「这是linux下运行的mysql软件包,可用于linux 下安装 php + m」· RESULT 代码 · 共 9 行

DROP TABLE IF EXISTS t1, t2;
CREATE TABLE t1 (id INTEGER, grp TINYINT, id_rev INTEGER);
SELECT COUNT(*) FROM t1;
COUNT(*)
4181000
SELECT COUNT(DISTINCT id) FROM t1 GROUP BY grp;
DROP TABLE t1;
set @@read_buffer_size=default;