2011年3月27日
Oracle中的Null(再提)
摘要： http://www.adp-gmbh.ch/ora/misc/null.htmlNULL in OracleA column in a table can be defined with thenot nullconstraint.See alsoNULLs and boolean operatorsnvl,nvl2andlnnvlare SQL constructs that are related to NULL handling.Theset nullcommand inSQL*Plusdefines how nulls are displayed in a resultset.Emp 阅读全文
posted @ 2011-03-27 07:36 张长胜 阅读(215) 评论(0) 推荐(0)