离散数学学习笔记——集合的符号表⽰离散数学学习笔记——集合的符号表⽰什么是集合A set is a group of objects. (simplest way)By a set we mean any collection M into a whole of definite distinctobjects m (which we called elements of M) of our pe
Oracle中解决selectinto值集为空的报错情况先看为空的情况procedure test isn number;beginselect 1 into n from CUX_2_OM_RELEASE_LIMIT_V covwhere cov.Customer_Id=null;刘德跃end;CUX_2_OM_RELEASE_LIMIT_V中没有id是空的,因此返回的结果⼀定是空集php5运⾏