这样的帖子,俺必须顶The CONCAT (concatenation) function appends two strings into one string. If one or the other string is null, the function returns the non-null string. If both strings are null, a null is returned. The function accepts two VARCHAR2 arguments and returns one VARCHAR2 value.PL/SQL Example:CONCAT ('abc', 'defg') ==> 'abcdefg' CONCAT (NULL, 'def') ==> 'def' CONCAT ('ab', NULL) ==> 'ab' CONCAT (NULL, NULL) ==> NULL
CONCAT (NULL, 'def') ==> 'def'
CONCAT ('ab', NULL) ==> 'ab'
CONCAT (NULL, NULL) ==> NULL