(select concat(chr(64)||chr(52)||chr(51)||chr(55)||chr(48)||chr(49)||user||chr(64)||chr(49)||chr(48)||chr(55)||chr(51)||chr(52) from DUAL))

What this expression does (in Oracle) is build a string of the form "@43701{USER}@10734", where {USER} is the current database user.

• chr(64) = @
• chr(52) = 4
• chr(51) = 3
• chr(55) = 7
• chr(48) = 0
• chr(49) = 1 So "@43701" is produced, then the current user, then "@10734" (where chr(64)||chr(49)||chr(48)||chr(55)||chr(51)||chr(52) gives "@10734").

The built value is essentially "@43701" || USER || "@10734", e.g. "@43701HR@10734" if the current user is HR. Note: in Oracle, USER is a function that returns the current username.

Correct syntax examples:

• Using concatenation with ||: select chr(64)||chr(52)||chr(51)||chr(55)||chr(48)||chr(49)||user||chr(64)||chr(49)||chr(48)||chr(55)||chr(51)||chr(52) from dual;

• Or more simply: select '@43701' || user || '@10734' from dual;

If you run it, you’ll get something like: @43701@10734 (where is your database user).