吱嘎zhī ɡā

A. 革兰氏染色阳性杆菌
B. 专性厌氧菌
C. 顶端芽胞
D. 羽毛样菌落
E. 产生特异性外毒素

A. You can use aggregate functions in any clause of a SELECT statement.
B. You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.
C. You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
D. You can pass column names, expressions, constants, or functions as parameters to an aggregate function.
E. You can use aggregate functions on a table, only by grouping the whole table as one single group.
F. You cannot group the rows of a table by more than one column while using aggregate functions.

A. 树状
B. 逻辑型
C. 层次型
D. 关系型