WHERE expressions supported natively

Developer Documentation Library > Data Model > Available DSCs > Relational MR database (RDB) CDSC > WHERE expressions supported natively

The Relational MR Database (RDB) CDSC supports some types of WHERE expression natively. That is, the CDSC includes the expression in the underlying SQL query that will be executed against the tables in the database schema. Native WHERE expressions can improve the performance of the RDB DSC 2, particularly when filtering data for tabulation (see IDataSet.Filter in the MDM Object Model Reference).

The WHERE expression types that are supported natively are shown in the following table. Support depends on the Relational MR Database CDSC schema (RDB DSC 2 or RDB DSC) in use in the connected data source:

Schema	Expression type	Examples
RDB DSC 2 or RDB DSC	Respondent.Serial system variable compared to a numeric value	Respondent.Serial >= 10000 Respondent.Serial < 2000

RDB DSC 2 only

Type	Logical (AND, OR)	=	< >	>	<	>=	<=	IS NOT NULL
mtLong		X	X	X	X	X	X	X
mtCategorical						X		X
Simple expression that is composed by a permitted expression	X

The variable that is being compared must be on the left-hand side of the comparison operator for both Long and Categorical comparisons. The variables must be in the HDATA top level, and mtCategorical only supports compare >=with {Single_Value}.