單項選擇題select count(*) from authors where city=’beijin’.對于上一條語句,下面表述是正確的()

A.從authors表中查詢出city是beijin,且名為count的記錄數(shù)目。
B.從authors表中查詢出city 是beijin的第一條記錄
C.從authors表中查詢出city 是beijin 的所有記錄
D.從authors表中查詢出city是beijin的記錄總數(shù)目。


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1.單項選擇題TRUNCATE TABLE 和 DELETE TABLE的區(qū)別是()

A.TRUNCATE TABLE 刪除數(shù)據(jù)后可以恢復,而DELETE 不可以恢復
B.TRUNCATE TABLE 刪除數(shù)據(jù)后不可以恢復,而DELETE 可以恢復
C.兩者刪除數(shù)據(jù)過后都可以恢復
D.兩者刪除數(shù)據(jù)后都不可以恢復

2.單項選擇題從authors 數(shù)據(jù)庫中查詢出所有au_id滿足前2個字符為”72”,第四個字符為”-“的作家的姓名,下面哪一條語句滿足條件()

A.select * from authors where au_id =”72_-%”
B.select au_id=72_-% from authors
C.select * from authors where au_id like “72*-%”
D.select * from authors where au_id like “72_-%” _代表任意一個字符

3.單項選擇題下面哪一條語句實現(xiàn)了下列功能:在authors數(shù)據(jù)庫中查找所有姓名以d 打頭的作家()

A. select * from authors where au_name=”d”
B. select “d” from authors
C. select * from authors where au_name like “d%”
D. select au_name like “d%” from authors

4.單項選擇題select au_id from authors where price<$15 or price >$ 20.下面哪一條語句與這一條語句執(zhí)行效果相同()

A. select au_id from authors where price IN($15,:$20);
B. select au_id from authors where price between $15 and $20
C. select au_id from authors where price not between $15 and $20
D. select au_id from authors where price not IN($15,$20);

5.單項選擇題select au_id from authors where state=”ca” or state=”ks”.下面哪一條語句與這一條語句執(zhí)行效果相同()

A. select au_id from authors where state IN(“ac”,:”sk”);
B. select au_id from authors where state between ac and sk
C. select au_id from authors where state not between ca and ks
D. select au_id from authors where state IN(“ca”,:”ks”);