Class Aggregate

Namespace: YndigoBlue.Velocity.Model

Assembly: YndigoBlue.Velocity.dll

Represents an aggregate function operation (COUNT, SUM, AVG, MIN, MAX) that can be used in expressions.

public class Aggregate : IElement

Inheritance: object

Aggregate

Implements: IElement

Examples

Using aggregate in an expression (advanced):

// Create an aggregate: SUM(price * quantity)
Expression priceQtyExpression = new Expression();
priceQtyExpression.Add(ordersTable["price"]);
priceQtyExpression.Add(new ArithmeticOperator(ArithmeticType.Multiply));
priceQtyExpression.Add(ordersTable["quantity"]);

Aggregate sumAggregate = new Aggregate(AggregateType.Sum, priceQtyExpression.Elements);

// Note: For this scenario, use Function instead:
Function sumFunction = new Function(FunctionType.Sum);
sumFunction.Add(ordersTable["price"]);
sumFunction.Add(new ArithmeticOperator(ArithmeticType.Multiply));
sumFunction.Add(ordersTable["quantity"]);

Preferred approach using Function:

// COUNT aggregate
Function countFunction = new Function(FunctionType.Count, ordersTable["id"]);
query.AddSelectItem(countFunction);

// SUM aggregate
Function sumFunction = new Function(FunctionType.Sum, ordersTable["total"]);
query.AddSelectItem(sumFunction);

// AVG aggregate
Function avgFunction = new Function(FunctionType.Avg, ordersTable["price"]);
query.AddSelectItem(avgFunction);

// MIN aggregate
Function minFunction = new Function(FunctionType.Min, ordersTable["price"]);
query.AddSelectItem(minFunction);

// MAX aggregate
Function maxFunction = new Function(FunctionType.Max, ordersTable["price"]);
query.AddSelectItem(maxFunction);

Remarks

Aggregate performs aggregate calculations on sets of rows, typically used with GROUP BY clauses. While Function is the more common way to use aggregate functions, Aggregate provides a lower-level building block for complex scenarios where aggregates need to be composed with other elements in expressions.

The supported aggregate types are:

CountCounts the number of rows
SumCalculates the sum of values
AvgCalculates the average of values
MinFinds the minimum value
MaxFinds the maximum value

For most use cases, prefer using Function with FunctionType aggregate types instead of using Aggregate directly. Aggregate is primarily used internally and in advanced scenarios.

Constructors

Aggregate(AggregateType): Creates a new aggregate without any elements.

Aggregate(AggregateType, IEnumerable<IElement>): Creates a new aggregate with multiple elements.

Aggregate(AggregateType, IElement): Creates a new aggregate with a single element.

Aggregate(AggregateType, params IElement[]): Creates a new aggregate with multiple elements.

Properties

AggregateType: Gets or sets the type of aggregate operation (Count, Sum, Avg, Min, Max).

Elements: Gets or sets the elements (columns, expressions, etc.) that the aggregate operates on.

Table of Contents

Class Aggregate

Examples

Remarks

Constructors

Properties