database测试笔试题1

乙醇 创建于 6 个月 之前

最后更新时间 2018-09-11

主键的值可以为空么?

can the value of primary key be NULL? no

答案 : 不行

创建索引是为了提高性能么?

Is the index used to improve the peformance? 答案:yes

答案: 是

关键字 select distinct 是用来分组的么?

is the keyword "select distinct" used to group result-set by one or more columns? no

答案: 不是

哪个关键字是用来对结果排序?

which keyword is used to sort the result-set? order by

答案 : Order by

哪个关键字是用来修改已经存在的数据?

which keyword is used to modify the existing records in table? update

答案: update

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