oracle group by語句實(shí)例測試

本文將詳細(xì)介紹oracle group by語句，以實(shí)例進(jìn)行測試，需要的朋友可以參考下

Sql代碼
代碼如下:
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;

總結(jié)：對于1，2而言，結(jié)果應(yīng)該是一樣的，但是分組的順序不同，SQL的性能應(yīng)該也是不同的。