题
我有一个邮政编码,存储在文本字段(字符串)中,并且想要仅在SELECT语句中仅选择值的最后3位数字。这可能吗?是否有标准方法是这样做,以便SQL是可互换的accross数据库?我将在Oracle上使用它在生产中,但我在Interbase上测试(是的,是的,我知道,两个完全差异DB,但那是我正在做的)
感谢您可以提供的任何帮助
解决方案
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
其他提示
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'