本文将详细介绍oracle group by语句，以实例进行测试，需要的朋友可以参考下
Sql代码
代码如下:
CREATE TABLE test(a VARCHAR2( 20),b VARCHAR2 (20),c NUMBER,d VARCHAR2 (20))
INSERT INTO test VALUES( ‘a1′,’b1’ ,1, ‘t’);
INSERT INTO test VALUES( ‘a3′,’b3’ ,3, ‘t’);
INSERT INTO test VALUES( ‘a4′,’b4’ ,4, ‘t’);
INSERT INTO test VALUES( ‘a2′,’b2’ ,2, ‘t’);
INSERT INTO test VALUES( ‘xx’,’xx’ ,5, ‘x’);
INSERT INTO test VALUES( ‘a1′,’b1’ ,1, ‘t’);
INSERT INTO test VALUES( ‘a3′,’b3’ ,3, ‘t’);
INSERT INTO test VALUES( ‘a4′,’b4’ ,4, ‘t’);
INSERT INTO test VALUES( ‘a2′,’b2’ ,2, ‘t’);
INSERT INTO test VALUES( ‘xx’,’xx’ ,5, ‘x’);
COMMIT;
1.SELECT a,b, SUM(c) FROM test WHERE d= ‘t’ GROUP BY a,b ORDER BY a,b;
2.SELECT a,b, SUM(c) FROM test WHERE d= ‘t’ GROUP BY b,a ORDER BY a,b;
总结：对于1，2而言，结果应该是一样的，但是分组的顺序不同，SQL的性能应该也是不同的。
