3.You need to extract details of those products in the SALES table where the PROD_ID column contains

3.You need to extract details of those products in the SALES table where the PROD_ID column

contains the string '_D123'.

Which WHERE clause could be used in the SELECT statement to get the required output?

A.WHERE prod_id LIKE '%_D123%' ESCAPE '_'

B.WHERE prod_id LIKE '%\_D123%' ESCAPE '\'

C.WHERE prod_id LIKE '%_D123%' ESCAPE '%_'

D.WHERE prod_id LIKE '%\_D123%' ESCAPE '\_'

答案:B

解析：这道题考察的是转意字符，oracle没有默认的转意字符，需要用escape来指定，指定成啥就是啥

并且，它只能是1个长度的字符，这道题问的是你怎么能知道pro_id列中包含_D123的记录，让你确定where条件，由于这里用了要找_,

而_表示的是一个任意字符，所以需要使用转意字符，选B

A.错误，这里相当与指定_为转意字符，对D进行转意了

B.正确

C.错误，escape只能指定长度为1的字符

D.错误，escape只能指定长度为1的字符