Oracle中 其語法為：
substr函式的用法，取得字串中指定起始位置和長度的字串 ，預設是從起始位置到結束的子串。
substr( string, start_position, [ length ] ) substr("目標字串",開始位置,長度)
如:
substr("This is a test", 6, 2) would return "is"
substr("This is a test", 6) would return "is a test"
substr("TechOnTheNet", -3, 3) would return "Net"
substr("TechOnTheNet", -6, 3) would return "The"select substr("Thisisatest", -4, 2) value from dual
Oracle中 其語法為：
substr函式的用法，取得字串中指定起始位置和長度的字串 ，預設是從起始位置到結束的子串。
substr( string, start_position, [ length ] ) substr("目標字串",開始位置,長度)
如:
substr("This is a test", 6, 2) would return "is"
substr("This is a test", 6) would return "is a test"
substr("TechOnTheNet", -3, 3) would return "Net"
substr("TechOnTheNet", -6, 3) would return "The"select substr("Thisisatest", -4, 2) value from dual