Using @ on Variable Names

Question

Googling I've found this DB2 Function declaration:

CREATE FUNCTION QGPL.SPLIT ( 
@Data     VARCHAR(32000), 
@Delimiter VARCHAR(5)
)

Whats means @ symbol before the Variable Name?

Regards,

Pedro

Answer 1

The @ character is simply the first character of the SQL identifier [variable name] naming the parameter defined for the arguments of the User Defined Function (UDF); slightly reformatted [because at first glance I thought that revision might make the at-symbols appear more conspicuously to be part of the name, though now I think probably not]:

 CREATE FUNCTION QGPL.SPLIT
 ( @Data      VARCHAR(32000)
 , @Delimiter VARCHAR(5)
 ) returns ...

Put simply, the use of the @ character in an identifier is highly discouraged; the use of such variant characters, although supported in standard object naming, they can cause great pains and difficulties, including some that are insurmountable:

http://www.ibm.com/support/knowledgecenter/api/content/ssw_ibm_i_71/db2/rbafzch2iden.htm

Identifiers
An identifier is a token used to form a name. An identifier in an SQL statement is an SQL identifier, a system identifier, or a host identifier. Note: $, @, #, and all other variant characters should not be used in identifiers because the code points used to represent them vary depending on the CCSID of the string in which they are contained. If they are used, unpredictable results may occur. [...]

[Edit-addendum 17May2015]

http://www.ibm.com/support/knowledgecenter/api/content/nl/en-us/SSEPGG_10.5.0/com.ibm.db2.luw.admin.dbobj.doc/doc/c0004625.html

Naming rules in a multiple national language environment
The basic character set that can be used in database names consists of the single-byte uppercase and lowercase Latin letters (A…Z, a…z), the Arabic numerals (0…9) and the underscore character (_).

This list is augmented with three special characters (#, @, and $) to provide compatibility with host database products. Use special characters #, @, and $ with care in a multiple national language environment because they are not included in the multiple national language host (EBCDIC) invariant character set. Characters from the extended character set can also be used, depending on the code page that is being used. If you are using the database in a multiple code page environment, you must ensure that all code pages support any elements from the extended character set you plan to use. [...]

[/Edit-addendum 17May2015]