Hello! I'm ippuku_time, a GIS implementation support consultant.
Welcome to the ninth installment of the "Learn SuperMap iDesktopX in 5 Minutes."
In the previous article, we explored thematic maps — a way to visualize data effectively. This time, we'll look at something like its reverse process: the query function, which allows you to efficiently search large datasets to find only the records that meet specific criteria. After all, the first step in data analysis is to extract the right data accurately.
GIS data consists of two key parts — spatial data, which contains location information, and attribute data, which holds descriptive details such as names or numerical values.
The query functions in iDesktopX are designed to handle both aspects, enabling you to interact with your data freely and extract just what you need.
Figure: Conceptual illustration of GIS queries — extracting only the data that meets defined conditions from a large dataset
1. Search by Attribute: "SQL Query"
SQL (Structured Query Language) is a global standard language for querying databases.
In iDesktopX, you can use SQL to find objects that match certain conditions based on their attribute table information.
(1) SQL Query Basics
You can specify conditions such as:
“Search for buildings with 30 or more floors in this dataset.”
“Display only stations on the JR Yamanote Line.”
iDesktopX provides a user-friendly interface that lets you construct SQL statements intuitively — even if you're not familiar with SQL syntax.
(2) Example: SQL Query Using Minato Ward Data
① Numeric Search
"floor number" >= 30
(Search for skyscrapers over 30 stories high using Minato Ward building data.)
② Character Search
"Line name" = 'Toei Oedo Line'
(Search for Toei Oedo Line stations from Minato Ward station data.)
③ Fuzzy Search (Wildcard)
"Facility Name" LIKE '%Art Museum'
(Search for facilities containing "museum" in their name.)
④ Multiple Conditions
"Land use" = 'Park' AND "Area" > 10000
(Search for parks with an area of 10,000 m² or more.)
2. Search by Location: "Spatial Query"
Spatial queries are a unique and powerful GIS capability that allow you to search data based on the spatial relationships between objects.
(1) Concept
You can perform location-based searches such as:
“All convenience stores within 500 meters of Roppongi Hills.”
“All facilities completely contained within Shiba Park.”
“All land parcels adjacent to National Route 1.”
(2) Representative Spatial Operators
To define spatial relationships, you can use the following operators:
① Intersect – Matches when two objects overlap (even slightly). This is the most common operator.
② Contains – Matches when one object completely contains another (e.g., Minato Ward contains Akasaka).
③ Within – Matches when one object is completely contained within another (e.g., Tokyo Tower is within Minato Ward).
④ Touches – Matches when boundaries touch but interiors do not overlap.
⑤ Disjoint – Matches when two objects are completely separate and not in contact.
3. Making the Most of Query Results
When you execute a query, the matching objects are highlighted on the map or filtered in the attribute table. More importantly, you can save the query results as a new dataset, allowing you to focus your subsequent analysis and visualization on the exact data you need.
Summary
In this article, we explored the Query function in iDesktopX, which enables efficient data retrieva1 from large GIS datasets. There are two main types of queries:
SQL Queries — for searching by attribute information
Spatial Queries — for searching by location
By mastering both, you can dramatically reduce the time spent exploring data and focus on deeper analysis.
In the next installment, we'll reach the very heart of GIS analytical capabilities:
Part 10: "Unleash the Potential of Data! An Introduction to Spatial Analysis."
We'll introduce powerful GIS analysis techniques such as buffer analysis and overlay analysis. Stay tuned!
For source and sample code: https://supermap-japan.blogspot.com/2025/09/9idesktopxsql.html
