Advanced SQL Selects

Welcome
MapInfo User Conference 2014: GIS Gets Personal
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Hands on Lab
13D Advanced SQL Selects
Peter Horsbøll Møller
GIS/LI Pre-Sales Specialist
June 13, 2014
Every connection is a new opportunity™
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Advanced
SQL Selects
Practice calculating
distances, object lengths
and other geographic
operations in SQL.
Learn how to use Sub-selects
and other advanced
features.

Geographic Measurements
MapBasic functions
• Area(OBJ, ”units”)
• ObjectLen(OBJ, ”units”)
• Perimeter(OBJ, ”units”)
• They also exist as Cartesian- & Spherical- versions
• Units: ”m”
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”km”
”in”
”ft”
”mi”
...
”sq m”
”sq km”
”hectare”
”sq ft”
”sq mi”
...

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Exercise
Data sets
•USStates.tab
•USUS_HIWay.tab
•Calculate the area of each state
•Calculate the perimeter of each state
•Calculate the length of each highway

Aggregations and Grouping
With the aggregations you can extract statistical
information from a number of records, such as Sum,
Average and Minimum or Maximum values
The aggregations often take a column as parameter.
Count(*), however, just takes a *
If you use an aggregation you’ll get just one row in the
result, unless you specify a column to group the result by
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Exercise
Data sets
•USStates.tab
•USUS_HIWay.tab
•Calculate the total area of all states
•Calculate the total area of the selected states
•Calculate the total length of the selected highways

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Joining Tables
When joining two tables thru a Select statement you need
to specify a join condition
This can be a alfanumerical join:
• TABLE1.ID = TABLE2.ID
or a spatial join:
• TABLE1.OBJ Intersects TABLE2.OBJ
The spatial object is taken from the first table in the join
statement

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Exercise
Data sets
•USStates.tab
•USUS_HIWay.tab
•Find the spatial join between highways and states, that is
which states does the highways intersect?
•How much of each highway (in miles) is within the
individual states?

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Sub Selections
A Sub Selection returns a value or a list of values that can
compared to bojects or alfanumerical values
A sub select has this structure:
Select * From TABLE1 Where COLUMN1
In (Select COLUMN1 From TABLE2)
Or
Select * From TABLE1 Where OBJ Intersects
Any (Select OBJ From TABLE2)

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Exercise
Data sets
•USStates.tab
•USUS_HIWay.tab
•Find the states that has one or more highways crossing
•Find the states that has no highways crossing

Measuring Distance
MapBasic functions
• Distance(xFrom, yFrom, xTo, yTo, ”units”)
• Exists also as Cartesian- & Spherical- versions
• Format$()
• Can be used to forse a larger number of decimals:
Format$(numeric_value, ”#.######”)
• CentroidX(object) / CentroidY(object)
• Extracts coordinates from the centroid of an object
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Exercise
Data sets
•USStates.tab
•USUS_HIWay.tab
•USSTATECAP.tab
•Find the distance from every state capital to Washington
•Find the distance from every state capital to Nashville

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Solutions
1 Select State_Name
, Area(obj, "sq mi") "Area sq miles"
from STATES into Selection
2 Select State_Name
, Area(obj, "sq mi") "Area sq miles"
, Perimeter(obj, "mi") "Perimeter miles"
3 Select Highway
, ObjectLen(obj, "mi") “Length miles”
from US_HIWAY into Selection
4 Select Sum(Area(obj, "sq mi")) "Area sq miles"

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Solutions
5 Select Sum(Area(obj, "sq mi")) "Area sq miles"
from Selection into __SUM
6 Select Sum(ObjectLen(obj, "mi")) “Length miles”
from Selection into __SUM
7 Select US_HIWAY.Highway, STATES.State_Name
from US_HIWAY, STATES
where US_HIWAY.Obj Intersects STATES.Obj
order by US_HIWAY.Highway, STATES.State_Name
into Selection

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Solutions
8 Select US_HIWAY.Highway, STATES.State_Name
, ObjectLen(Overlap(US_HIWAY.Obj, STATES.Obj), "mi") "Length Miles"
from US_HIWAY, STATES
where US_HIWAY.Obj Intersects STATES.Obj
order by US_HIWAY.Highway, STATES.State_Name
into Selection
9 Select State_Name
from STATES
where OBJ Intersects Any (Select OBJ From US_HIWAY)
order by State_Name
into Selection

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Solutions
10 Select State_Name
from STATES
where not OBJ Intersects Any (Select OBJ From US_HIWAY)
order by State_Name
into Selection

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Solutions
11 Set CoordSys Table STATECAP
‘Select Washinton
Fetch First From Selection
Print Format$(CentroidX(Selection.obj), "#.######")
+ ", " + Format$(CentroidY(Selection.obj), "#.######")
Select Capital, State
, Distance(-77.016167, 38.90505, CentroidX(OBJ), CentroidY(OBJ), "mi")
"Distance To Washington"
from STATECAP into Selection

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