1. Lab 7: Attribute SQL- Query the database
You have been asked to determine which parcel properties have a market
value greater than $75,000.
You have been asked to find these properties and display on a map
within your study area.
How will you find the properties & display on a map using MapInfo?
In this lesson, you will learn how to ask questions/ query the attribute
table data using query menus to build SQL (structured query language).
You will also learn what a relational join is and how to perform a
relational join.

2. To query data in MapInfo, use Query> Select for simple selections:
In this example, we want to find Census blocks that have >= 100 persons
1 First select File> open table
2 Select Query> Select 2 3
3 Select table
4 Select assist
to write query 4 5 7 6 9 8
5 Select the column “population”
6 Select the operator “>=“
7 Type the value “100”
8 Verify the syntax
9 Select Ok
10 Select OK to find the answer (next Slide) 10

3. The Query > Select result in parcels with “population >= 100” displays
as a browser and each block highlighted on the map.
The query results can be saved as a new table, discarded, or
the syntax can be saved in a query template.

4. brief description of the options.
To query data in MapInfo, use Query> SQL Select for more complex selections.
Shown below is the Query> SQL Select screen example from MapInfo with a
brief description of the options. * 1b * 2b 1a 3 4 2a 5 6
Select File>Open> select table, select Query> SQL Select 1a Highlight From Tables box
1b Select table from tables pop up (table appears in From Tables box)
2a Move cursor to where Condition box; 2b Select column required from columns menu pop up
& the column (totalpopulation) displays in the where condition window
3 Select operator (=,>,<,*,/,etc) from Operators menu pop up (operator appears in where condition)
4 Type the value in the where condition box (In this case )
5 Select other options (Here we are sorting by field totalpopulation so select Order by columns,
select the columns button and select the column to sort by
6 Select Ok – The results of the query are displayed as records in a browser & highlighted on map
(See results on next Slide)

5. The results of the Query>SQL Select– cities where the total population is <= 25,000:
A browser called Query1 is created that meets the SQL conditions (48 cities)
and a map showing the 48 cities are highlighted
Also, note that the cities are sorted in ascending (increasing) value by total population

6. A common relational join using Query> SQL Select in MapInfo:
Join the parcel polygon file to the Auditor’s parcel characteristics table.
Open the tables that you wish join
Determine the fields that are a common link

7. Relational Join – MapInfo example (continued)
3 Select Query> SQL Select
4 Select tables to join
5 type where condition or choose
from column button parcel.ppn
choose operator button =
from column button audattr.parcel
6 Verify syntax
7 Select OK
8 Query runs: results in a browser
and polygons highlighted that met
requirements. Query 1 can then
be saved to a new table. 3 4 5 6 7 8

8. You are now ready to begin MapInfo Exercise- Lab 7
Attribute SQL. The main objectives are:
To ask questions or query the attribute table using:
Query> Select Menu (for simple questions)
Query> SQL Select Menu (complex questions)
Begin exercise- lab 7