Aggregate Function Data Type

 SUM() AVG() Return Type Real/Float. So it is unprecise number.

 

另外， teradata会自动先把NULL删除后再对剩下的数据集合进行AVG(a), MAX(a), MIN(a), SUM(a), COUNT(a)。

 

如下例：

DROP TABLE guanwang_test_avg;
CREATE TABLE guanwang_test_avg
( a INTEGER)
;
INSERT INTO guanwang_test_avg VALUES(1);
INSERT INTO guanwang_test_avg VALUES(0);
INSERT INTO guanwang_test_avg VALUES(NULL);
SEL AVG(a), MAX(a), MIN(a), SUM(a), COUNT(a) FROM guanwang_test_avg；

 

Average(a)    Maximum(a)    Minimum(a)    Sum(a)    Count(a)
0.50              1                      0                    1              2