View tables – Pitney Bowes MapXtreme User Manual

Page 177

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Chapter 8: Working with Data

Table Metadata (TableInfo)

MapXtreme v7.1

184

Developer Guide

Dim ti As TableInfoServer = New TableInfoServer("StateCapXY",_

"SRVR=tempest;UID=tn;PWD=tn", "Select * from usa_caps", _
MapInfo.Data.ServerToolkit.Oci)

Dim StateCapXY As Table = Connection.Catalog.OpenTable(ti)

' Add the Oracle columns to the USA table
Dim states As Table = Connection.Catalog.GetTable("usa")
states.AddColumns(Nothing, MapInfo.Data.BindType.Static, _

StateCapXY, "state", MapInfo.Data.Operator.Equal, "state")

'Create a ranged theme on the USA layer using a field
'from the Oracle table

Dim thm As MapInfo.Mapping.Thematics.RangedTheme = New _

MapInfo.Mapping.Thematics.RangedTheme(lyr, _
"pop_1990", "popusa", 4, _
MapInfo.Mapping.Thematics.DistributionMethod.EqualCount_
PerRange)

lyr.Modifiers.Insert(0, thm)

'Create a legend to appear on the map

Dim legend As MapInfo.Mapping.Legends.Legend = _

map.Legends.CreateLegend(New Size(5, 5))

legend.Border = True
Dim frame As MapInfo.Mapping.Legends.ThemeLegendFrame = _

MapInfo.Mapping.Legends.LegendFrameFactory.CreateTheme_
LegendFrame(_"Pop", "pop", thm)

legend.Frames.Append(frame)
frame.Title = "pop"
map.Adornments.Append(legend)

End Sub

View Tables

A view is a way to relate information from one or more tables based on a named select statement.
The Catalog allows you to create views based on any table definition. View tables have the following
characteristics:

The data is not copied.

Access to views always accesses its base tables.

View is an MapInfo SQL Select Statement with a name (Alias).

Queries may be joins (forms composite keys).

Membership in the View is live.

Exception: Views that aggregate cache the data. Data changed events trigger recomputation.

Can be serialized and persisted in workspaces.

For more information and code examples, see the MapInfo.Data.TableInfoView class in the
Developer Reference Help system.

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