A reference to a column in an expression.
A column might comprise another expression, or a reference to a database field.
Format
column-ref [ -> ColumnName ]*
Remarks
column reference in an expression consists of a column-ref, optionally followed by one or more de-reference operators.
The de-reference operator "->" returns a value from the target of a reference column.
As a dynamic list update is not supported for de-referenced columns, a list is not refreshed automatically.
1. Examples of column references used in expressions:
CurrentValue
"ParentGroupId"->FullName
Id->FullName
2. Example of de-reference operator used to avoid the need for a join:
SELECT ParentGroupId->Name, Name
FROM CPointAlg
3. There is a known limitations when using the de-reference operator in the WHERE clause of a historic query, for example the following query will be blocked:
SELECT *
FROM CDBHistoric
WHERE Id->FullName LIKE 'My Points.%'
The query processor currently doesn't recognize the de-reference operator as optimizable. The access plan for the above query would be full table scan, which would be blocked as an unconstrained historic search.