문자열의 추출 부분을위한 SQL

Question

텍스트 필드 (문자열)에 저장된 zipcode가 있고 select 문에서 값의 마지막 3 자리 만 선택하고 싶습니다.이것이 가능한가?SQL이 동시에 Accross 데이터베이스를 교환 할 수 있도록 표준 방법이 있습니까?나는 오라클에서 생산할 때 그것을 사용할 것입니다. 그러나 나는 Interbase (예, 예, 알아, 두 개의 완전히 diff dbs, 내가하고있는 것)

를 제공 할 수있는 도움을 주셔서 감사합니다.

Answer 1

Assuming the zipcodes all have the same length, you can use substr.
If they don't have the same length, you have to do similar things with the strlen function.

Interbase does not have a built-in substring function, but it does have a UDF (user defined function) called SUBSTR in lib_udf.dll that works like this:

select substr(clients.lastname, 1, 10)
from clients

You declare the UDF like this:

DECLARE EXTERNAL FUNCTION SUBSTR
    CSTRING(80),
    SMALLINT,
    SMALLINT
RETURNS CSTRING(80) FREE_IT
ENTRY_POINT 'IB_UDF_substr' MODULE_NAME 'ib_udf';

Oracle does have a built-in substr function that you use like this:

select substr(clients.lastname, 1, 10)
from clients

--jeroen

Answer 2

This depends on how your storing the zip code. If you are using 5 digits only then this should work for Oracle and may work for Interbase.

select * from table where substr(zip,3,3) = '014'

IF you store Zip + 4 and you want the last 3 digits and some are 5 digits and some are 9 digits you would have to do the following.

select * from table where substr(zip,length(zip) -2,3) = '014'

and one option that may work better in both databases is

select * from table where zip like '%014'