Using the FROM clause
The FROM
clause is an optional clause, unless you want to apply filtering (by using the WHERE
clause). The WHERE
clause is used to specify the source(s) upon which the query needs to be executed. Mostly, the WHERE
clause is used to select a collection. The FROM
clause is needed when you want to query a collection.
Another example of using the SELECT
statement without the FROM
clause is the following code snippet:
SELECT CONTAINS(UPPER("Riccardo"), UPPER("ri"))
This SELECT
statement only operates on string values and uses some of the built-in functions that DocumentDB provides (CONTAINS
and UPPER
). The output of this SELECT
statement is as follows:
[ { "$1": true } ]
Potentially, you could use DocumentDB only for its built-in functions, but it would be an expensive solution.
Aliasing
Collections can be aliased by applying the AS
operator:
SELECT p.FirstName, p.LastName FROM PersonInformation AS p
Once we decide to use aliasing, we can no longeruse PersonInformation
as...