Select Clause
In the select clause, you specify columns that will appear in the query results.
In the example, a select
clause projects two columns, address
and name
, properties of the concept /customer
. The alias for the customer concept is the letter c
:
select c.name, c.address from /customer c
You can also give each projection an alias, for example:
select c.name as name
The use of the optional "as
" makes the code more readable.
In the select
clause you can use the following:
- Literal values
- Catalog functions and rule functions
- Entities that are declared in the
from
clause, unless you are using agroup by
clause (see Group by Clause)
You can use an optional limit
clause to specify the maximum number of rows to return, and you can use an offset
to ignore the first n
rows.
You can use an optional distinct
clause to prevent the query from returning duplicate rows.
Examples of Select Clauses
These examples show only the select
clause. A complete query requires a select
and a from
clause. (# is the escape character. See Keywords and Other Reserved Words.)
select A.* select {limit: first 10} A.name select /#DateTime/now() as C select /RuleFunctions/GetState() as D select /#String/concat(B.customerId,”ABC”) as E select B.*, A.custId id, B@extId as extId