Programming Guide - Actian

How You Can Declare a Composite Field's Array Variable DynamicallyBecause table fields must always contain at least one column, you can neverdelete all columns from a table field. Therefore, replacing all of a table field'scolumns with another set of columns requires the following steps:1. Delete all but one column.2. Add the new columns.3. Remove the last of the original columns.The following code performs these operations:for i = tfield.TableBody.ChildFields.LastRow downto2 do tfield.DeleteColumn(position = i);endfor;insert new columns, beginning with position 1tfield.DeleteColumn(position =tfield.TableBody.ChildFields.LastRow);How You Can Declare a Composite Field's Array VariableDynamicallyTo change the fields in a composite field or the columns in a table fielddynamically at runtime, the composite field (including table fields) must havebeen created without a variable declared. Only after the composite field hasbeen modified to contain the required fields or columns should you use theDeclareData method to declare a user class or array variable for it.Moreover, to change the fields of a composite field or the columns of a tablefield whose user class or array variable has been dynamically declared, use theUnDeclareData method to remove the current user class or array beforechanging the fields or columns and declaring a new user class or array.The following sections describe dynamically declaring and undeclaring an arrayvariable for a table field.How You Can Declare and Undeclare DataBefore you can load data into a dynamically created or modified table field,perform the following operations:1. Attach the table field to the form by parenting it (if it is not alreadyparented).2. Specify the table field's underlying array with the DeclareData method.380 Programming Guide