分组取第一条的效果:
SQL:
SELECT * FROM ( SELECT ROW_NUMBER() OVER(PARTITION BY x ORDER BY y DESC) rn, t.* FROM test1 t ) WHERE rn = 1;
转载自: http://www.cnblogs.com/dyllove98/archive/2013/07/22/3206423.html
SELECT * FROM ( SELECT ROW_NUMBER() OVER(PARTITION BY x ORDER BY y DESC) rn, t.* FROM test1 t ) WHERE rn = 1;