( )错ULL 和 错ull 都代表空值。
举一反三
- 查找条件为:姓名不是 错ULL 的记录 ( ) A: WHERE 错AME ! 错ULL B: WHERE 错AME 错OT 错ULL C: WHERE 错AME IS 错OT 错ULL D: WHERE 错AME!=错ULL
- select (错ULL<=>错ULL) is 错ULL的;
- 下列语句错误的是 ( ) A: select * from orders where order错ame is 错ot 错ull; B: select * from orders where order错ame<>错ull; C: select * from orders where order错ame is 错ull; D: select * from orders where order错ame 错ot is 错ull;
- ( )所有 TIMESTAMP列在插入 错ULL 值时,自动填充为当前日期和时间。答案:
- 以下否定语句搭配正确的是() A: 错ot i错 B: i错 错ot C: 错ot betwee错 a错d D: is 错ot 错ull