[GIS] Check if an object is empty in mapbasic

mapbasicmapinfosql

I have mapbasic code that manipulates the obj-column in a point-table. Some rows doesn't have any geometry so the obj-column is empty. My question is how to check if there is no object?

All the methods i found in the mapbasic-reference that givs information about the obj-column, like ObjectInfo(), try to access the object which givs an error since there is none.

Is there any way to use SQL to select the rows with non empty obj-columns?

Regards

Best Answer

Query For Selecting row(s) without object :

    Select * from 'MYTABLE' where not obj into MYTABLE_NO_MAP_OBJECT   
    Browse * From MYTABLE_NO_MAP_OBJECT

Query For Selecting row(s) with object :

     Select * from MYTABLE where obj into MYTABLE_MAP_OBJECT
     Browse * From MYTABLE_MAP_OBJECT

Related Solutions

[GIS] Finding text object variable names in MapInfo/MapBasic

I have done this but as far as I know you have to select the text object using the text that is in that object. Here is some example code which finds an object by looking for the the text in the variable searchText:

Dim searchText, newText as String
Dim oLayout As Object
strLayWinName = WindowInfo(WindowID(FrontWindow()), WIN_INFO_TABLE)
searchText = "@01"
newText = "Text I want to add to the text object"

select * from strLayWinName where val(str$(objectinfo(object,1))) = 10 into strLaySel noselect
select * from strLaySel where Left$(str$(objectinfo(object,3)),Len(searchText)) = searchText into strLayObjSel

oLayout = strLayObjSel.object ' put the selected object into an object variable called oLayout
alter object oLayout info 3, searchText + " " + newText ' where new text is a string variable of your new text
update selection set object = oLayout

To expand on this, the way I use this code is to create a text object on a layout with some standard text at the front of it (for example I place an @ symbol and a number, so on the layout the text would read "@01 Text I want in the text object"). Then I place a white rectangle object on the layout over the "@01" part of the string to hide this.

When using the above code, the searchText variable is set to "@01" and the 7th line of code finds the text object where the first 3 characters are equal to "@01". Once you have this object, it sets its new value to the searchText plus whatever you want to change the remainder of the text object to which you set in the newText variable. If you give all of the text objects on the layout different numbers, then you can refer to them uniquely by checking the first 3 characters of the string. I have edited the code a little to make it clearer.

I know its not a particularly pretty way to do it, but it does work well.

[GIS] Compare two tables. Show values only in one table

Let's say we have two tables: Tab1 with field Field1, Tab2 with field Field2.

We want to select records from Tab1 which Field1 values is not present in Field2 of Tab2.

In MapInfo: menu Query->SQL Select...

Columns: *
from Tables: Tab1
where Condition: not Field1 in (select Field2 from Tab2)

In MapBasic window it will be: Select * from Tab1 where not Field1 in (select Field2 from Tab2) into Selection

Best Answer

Related Solutions

[GIS] Finding text object variable names in MapInfo/MapBasic

[GIS] Compare two tables. Show values only in one table

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