Microsoft Dynamics AX 2012 R3 Development-3 Locus IT Services

Microsoft Dynamics AX 2012 R3 Development-3

Locus IT ServicesMicrosoft Dynamics AX 2012 R3 Development-3

Lesson 6 : Computed Columns in Views

Computed Columns in Views

A view is a selected number of fields that come from one or more related tables. Microsoft Dynamics AX can also display a computed column based on fields in those tables. A computed column generates TSQL code at compile time and adds it to the TSQL code generated by the view, which increases performance.

This walkthrough describes how you can add a computed column to a view in Microsoft Dynamics AX.

A computed column is the output of a computation that inputs a regular column. For example, suppose your table has a column that is named AnnualRent. Your view could return that is named MonthlyRent and which calculates AnnualRent/12.

You can add the computed column to the select list of columns only. If the computed column is itself a select statement with a where clause, you can include the name of a real column in that where clause.

Prerequisites:

To fully understand this walkthrough you must know how to do the following:

  • How to use the Application Object Tree (AOT).
  • How to write an method in X++.

This topic also explains how you can add a computed column to a union view in Microsoft Dynamics AX. When a T-SQL union is involved, the support method that generates the T-SQL code for the computed column must input an int parameter. The parameter specifies one particular branch of the union query of the view. The T-SQL code that the method must output often differs depending on the branch.

This walkthrough illustrates the following tasks:

  • Create a union query.
  • Create the view with regular columns.
  • Add a computed column to the union view.
  • Examine the T-SQL code that is generated for the view.
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