Have picked up someone's code and this is a part of a where clause, anyone know what the double colon indicates?
b.date_completed > a.dc::date + INTERVAL '1 DAY 7:20:00'4 Answers
It varies based on RDBMS, but if I guess right, that's PostgreSQL, in which case the :: converts a.dc to a date type of date.
In other flavors...
In MS SQL Server 2000:
For built-in user-defined functions that return a table, the function name must be specified with a leading double colon (::) to distinguish it from user-defined functions that are not built-in. It also must be specified as a one-part name with no database or owner qualifications. For example: SELECT * FROM ::fn_helpcollations() b.. For built-in user-defined functions that return a scalar value, the function name must be specified as a one-part name (do not specify database or owner). Do not specify a leading double colon (::).
In MS SQL Server 2005:
Double-colons are no longer required for UDFs that return a table.
However...
Double-colons are required in SQL Server 2005 when granting permissions on schemas, certificates, endpoints, and a few other securables.
As well as...
When using User-Defined Types, static methods of the type must be called using the double-colon syntax.
Sources: BOL and Kalen Delaney's Blog
1In this case, it is a cast to a date type. :: is a type cast that can also be represented as CAST(expression AS type).
3It is a CAST operation(cast to a date type).
Example:
SELECT now()::timestamp(0);
Is equivalent to:
SELECT CAST (now() AS timestamp(0));They both result in casting now() to timestamp in the following format: YYYY-MM-DD HH:MM:SS
It is probably a cast, converting a.dc to type date.
IBM Informix Dynamic Server (IDS) would work that way - but the INTERVAL notation at the end is not valid for IDS, so presumably this is in fact another DBMS (probably PostgreSQL).
