Oracle Lead/Last函数1. SyntaxPurpose FIRST and LAST are very similar functions.Both are aggregate and analytic functions that operate on a set of values froma set of rows that rank
Shell中的()和(())小括号()1. 命令组,作为一个子shell顺序执行,如(date;ls);2. 命令替换,就是常用的``,$(date);3. 初始化数组,A=(a b c d)双括号(())1. 整数扩展,用于判断,A=3B=4if ((A>=B));then echo 1else echo 2fi常用测试符号>:大于<=:小于或等于>
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