What is the usage of the LEAD window function in EF Core 3.1 PostgreSQL?

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The LEAD window function is used to get the value of a column from the next row in the query result based on the current row. It is commonly used in scenarios where you need to compare a value in the current row with the next row.

In EF Core 3.1 PostgreSQL, the LEAD window function can be used with the FromSqlRaw or FromSqlInterpolated methods to execute raw SQL queries against the database.

For example, the following query uses the LEAD function to get the next order date for each customer:

var customers = await context.Customers
    .FromSqlRaw("SELECT Id, Name, OrderDate, LEAD(OrderDate) OVER (PARTITION BY Name ORDER BY OrderDate) AS NextOrderDate FROM Orders")
    .ToListAsync();

This query returns a list of customers with their order date and the next order date for each customer based on the order date sorting. The LEAD function is used to get the next order date for each customer by partitioning the result by customer name and ordering by order date.