Log

2005
2008
2012
2014
2016
2017
2019
2022

2005, 2008
2012, 2014, 2016, 2017, 2019, 2022

Log (Logarithm) Mathematical Function

Use the Log function to return the natural logarithm of the specified expression.

Syntax

db.fx.Log({expression})

Arguments

expression: – The value to use in the logarithm calculation.

Returns

float

Examples

Select Statement

Select the natural logarithm of a product's weight (which is nullable in the database).

float? result = db.SelectOne(
        db.fx.Log(dbo.Product.Weight)
    )
    .From(dbo.Product)
    .Execute();

Where Clause

Select the natural logarithm of a product's depth (which is nullable in the database).

float? result = db.SelectOne(
        db.fx.Log(dbo.Product.Depth)
    )
    .From(dbo.Product)
    .Execute();

Order By Clause

Select and order by the natural logarithm of a product's depth.

IEnumerable<Product> result = db.SelectMany<Product>()
    .From(dbo.Product)
    .OrderBy(db.fx.Log(dbo.Product.Depth).Desc())
    .Execute();

Group By Clause

Select product details grouped by product category and the natural logarithm of the product's depth.

IEnumerable<dynamic> results = db.SelectMany(
        dbo.Product.ProductCategoryType,
        db.fx.Log(dbo.Product.Depth).As("calculated_value")
    )
    .From(dbo.Product)
    .GroupBy(
        dbo.Product.ProductCategoryType,
        db.fx.Log(dbo.Product.Depth)
    )
    .Execute();

Having Clause

Select the ids of all products, grouped by product category type having a natural logarithm of the product's height greater than the product's width.

IEnumerable<ProductCategoryType?> results = db.SelectMany(
        dbo.Product.ProductCategoryType
    )
    .From(dbo.Product)
    .GroupBy(
        dbo.Product.ProductCategoryType,
        db.fx.Log(dbo.Product.Height),
        dbo.Product.Width
    )
    .Having(
        db.fx.Log(dbo.Product.Height) > dbo.Product.Width
    )
    .Execute();