Returns a count of all distinct non-null values specified by the expression, evaluated in the context of the given scope.
You can create and modify paginated report definition (.rdl) files in Report Builder and in Report Designer in SQL Server Data Tools. Each authoring environment provides different ways to create, open, and save reports and related items.
CountDistinct(expression, scope, recursive)
(Variant) The expression on which to perform the aggregation.
(String) Optional. The name of a dataset, group, or data region that contains the report items to which to apply the aggregate function. If scope is not specified, the current scope is used.
(Enumerated Type) Optional. Simple (default) or RdlRecursive. Specifies whether to perform the aggregation recursively.
Returns an Integer.
The value of scope must be a string constant and cannot be an expression. For outer aggregates or aggregates that do not specify other aggregates, scope must refer to the current scope or a containing scope. For aggregates of aggregates, nested aggregates can specify a child scope.
Expression can contain calls to nested aggregate functions with the following exceptions and conditions:
Scope for nested aggregates must be the same as, or contained by, the scope of the outer aggregate. For all distinct scopes in the expression, one scope must be in a child relationship to all other scopes.
Scope for nested aggregates cannot be the name of a dataset.
Expression must not contain First, Last, Previous, or RunningValue functions.
Expression must not contain nested aggregates that specify recursive.
For more information about recursive aggregates, see Creating Recursive Hierarchy Groups (Report Builder and SSRS).
The following code example shows an expression that calculates the number of unique non-null values of
Size for the default scope and for a parent group scope. The expression is added to a cell in a row that belongs to the child group
GroupbySubcategory. The parent group is
GroupbyCategory. The expression displays the results for
GroupbySubcategory (the default scope) and then for
GroupbyCategory (the parent group scope).
Expressions should not contain actual carriage returns and line breaks; these are included in the example code to support documentation renderers. If you copy the following example, remove carriage returns from each line.
="Distinct count (Subcategory): " & CountDistinct(Fields!Size.Value) & "Distinct count (Category): " & CountDistinct(Fields!Size.Value,"GroupbyCategory")
Expression Uses in Reports (Report Builder and SSRS)
Expression Examples (Report Builder and SSRS)
Data Types in Expressions (Report Builder and SSRS)
Expression Scope for Totals, Aggregates, and Built-in Collections (Report Builder and SSRS)