Simplified Query Language Syntax
This section briefly describes the syntax of the query language so that you can quickly move on to the next section, Example Queries. When you are ready to learn about the syntax in more detail, see the section Full Query Language Syntax.
A select query has six clauses: SELECT, FROM, WHERE, GROUP BY, HAVING, and ORDER BY. The SELECT and FROM clauses are required, but the WHERE, GROUP BY, HAVING, and ORDER BY clauses are optional. Here is the high-level BNF syntax of a query language query:
QL_statement ::= select_clause from_clause [where_clause][groupby_clause][having_clause][orderby_clause]
The FROM clause defines the scope of the query by declaring one or more identification variables, which can be referenced in the SELECT and WHERE clauses. An identification variable represents one of the following elements:
An element of a collection relationship
An element of a single-valued relationship
A member of a collection that is the multiple side of a one-to-many relationship
Update and Delete Statements
Update and delete statements provide bulk operations over sets of entities. They have the following syntax:
update_statement :: = update_clause [where_clause] delete_statement :: = delete_clause [where_clause]
The update and delete clauses determine the type of the entities to be updated or deleted. The WHERE clause may be used to restrict the scope of the update or delete operation.