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Let Clause (Visual Basic)

  • บทความ

Computes a value and assigns it to a new variable within the query.

Syntax

Let variable = expression [, ...]

Parts

Term Definition
variable Required. An alias that can be used to reference the results of the supplied expression.
expression Required. An expression that will be evaluated and assigned to the specified variable.

Remarks

The Let clause enables you to compute values for each query result and reference them by using an alias. The alias can be used in other clauses, such as the Where clause. The Let clause enables you to create a query statement that is easier to read because you can specify an alias for an expression clause included in the query and substitute the alias each time the expression clause is used.

You can include any number of variable and expression assignments in the Let clause. Separate each assignment with a comma (,).

Example

The following code example uses the Let clause to compute a 10 percent discount on products.

Dim discountedProducts = From prod In products
                         Let Discount = prod.UnitPrice * 0.1
                         Where Discount >= 50
                         Select prod.ProductName, prod.UnitPrice, Discount

For Each prod In discountedProducts
    Console.WriteLine("Product: {0}, Price: {1}, Discounted Price: {2}",
                      prod.ProductName, prod.UnitPrice.ToString("$#.00"),
                      (prod.UnitPrice - prod.Discount).ToString("$#.00"))
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See also