How can i get the index of a point which is in my LineString?
I am using SQL Server 2008 R2.
I do have a geography type where a LineString is saved in.
I want now to get the index of two points on this LineString. So that I know which one occurs first.
Is this somehow possible?
Because right now i'm doing it for my self with a while loop... but it's really slow when i've got some more data in my database :/
EDIT: Ok, right now i'm trying to follow the solution from SQL to use CHARINDEX.
Some more background info:
I do have a geo point, I do have a linestring. I did get the intersecting points with a radius around my point from the linestring. Ok, now i want to try to get with the first intersecting point the index from this point on the LineString.
So i do have in my linestring some numbers like these patterns "1.123456 or 12.123456 or 123.123456" and my search point is also something like "1.123456 or 12.123456 or 123.123456"
The Problem is, that STIntersection gives me some different numbers back which are variable at the fractional digits. I thought about some string formatting, but i don't know how i should solve this. If there would be some nice regex features i think it would make my life easyier :)
I had a look through all of these functions but couldn't find anything for my needs.
Maybe some more experienced people could help me with that.
Thanks!
In case the datatype is varchar used. Please see below.
You can use CharIndex
DECLARE #document varchar(64)
SELECT #document = 'abcdef12345wuerzelchen'
SELECT CHARINDEX('abc', #document)
Once you have got the first occurrence point, Now you can check for another.
Declare #position int
Set #position = CHARINDEX('abc', #document)
SELECT CHARINDEX('wuerzelchen', #document, #position)
For more information you can check here
Related
I have a SQL table with a geography column. When I look at one of the rows the geography shows as a long hex string: 0xE6100....C0.
I want to write a query that finds all other rows in my database that have this same value. How can I do this?
I tried adding WHERE location = '0xE6100....C0' with and without quotes but I get an error:
Invalid operator for data type. Operator equals equal to, type equals geography.
Note: I'm just doing this query in an ad-hoc fashion I'm not really looking for a optimal solution or a way to parameterize this in any way. I just have a row that I'd like to find related values.
Looks like you need to use .STEquals
Check the documentation here
I have a string column where I need to find the substring until the first '-' is found.
Example column ELOT-IGS-2. I need to get "2" as output.
These columns come from a table so I cannot declare the variable as a fixed string.
I tried LOCATE, SUBSTRING_INDEX but none are build in functions.
I also tried RIGHT(ID_BETSLIP,CHARINDEX('-',ID_BETSLIP)-1) but this does not work when I have 2 times "-"
Does anyone have an idea?
select RIGHT(<your Field>, CHARINDEX('-',REVERSE(<your Field>))-1)
DECLARE #t varchar(20) = 'ELOT-IGS-2'
select REVERSE(SUBSTRING(reverse(#t),0,CHARINDEX ('-',REVERSE(#t))))
Simplest would be
select SUBSTRING(reverse(ELOT-IGS-2),0,charindex('-',reverse(ELOT-IGS-2)))
Based on #mohan111's solution you can add REVERSE in order to get what you need
DECLARE #t varchar(20) = 'ELOT-IGS-2'
select REVERSE(SUBSTRING(reverse(#t),0,CHARINDEX ('-',REVERSE(#t))))
You should have done this yourself, once you got #mohan111's solution! For your own improvement you can not ask for everything :-( Once you got a solution that is almost what you need, it is time to try to improve it yourself. Please check this MSDN page, and every time that you need to parse a string, START HERE :-) Try to go over the functions and maybe you will find the solution.
The REVERSE query and most string parsing function are not good solution in SQL Server, and in most cases you are better to do this using SQLCLR function.
I'm using postgresSQL with postgis and I'm trying to create a polygon with a hole. I read a lot of users asking for something similar, but I can't do it for myself. My code is
insert into distritos(nombre,geom) values ('Distrito6',ST_MakePolygon(ST_GeomFromText('LINESTRING((-15.66486 27.91996, -15.60610 27.91820, -15.60359 27.97169, -15.66586 27.97144,-15.66486 27.91996),(-15.65753 27.95894, -15.61610 27.95995, -15.61459 27.93157, -15.65477 27.27.93007,-15.65753 27.95894))',4258)));
but it doesn't work. What do I have to do?
A Polygon has a double parenthesis at the start and end, and inner rings are delineated by using single pairs of parenthesis, between commas, ie, ),( whereas a Linestring only has one set of parenthesis at the beginning and end. You are actually using the syntax for a MultiLinestring, which is probably where your issue is. You can fix you query like this:
insert into distritos(nombre, geom) values
('Distrito6', ST_GeomFromText('POLYGON((-15.66486 27.91996,
-15.60610 27.91820, -15.60359 27.97169, -15.66586 27.97144,-15.66486 27.91996),
(-15.65753 27.95894, -15.61610 27.95995, -15.61459 27.93157,
-15.65477 27.93007,-15.65753 27.95894))',4258));
Also, you do not need to use ST_MakePolygon, as if you are using ST_GeomFromText, you can create the polygon directly by using POLYGON instead of LINESTRING in your example above. ST_MakePolygon is probably more useful when you have arrays of Linestrings representing inner rings.
The Wikipedia WKT article details this very clearly, with WKT and accompanying graphics.
NOTE: You also have an error in you linestring, you have a repeated 27. in 27.27.93007.
I'm trying to write a SQL query which determine if a given point is into a polygon. (I'm using SQL Server 2008 R2).
I was following this tutorial (just copy / paste it and change some table name) and it approximatively works BUT it is not precise at all. For example, let's considerate a given point which coordinates are :
P = 45.7664, 4.87383.
If you draw a little polygon (an approximate square) around this point with 4 vertices coordinates :
S = 45.97215 4.693909, 45.687 4.674683, 45.73302 5.460205, 46.05227 5.366821, 45.97215 4.693909
the procedure given in the link below answers the point is NOT in polygon, whereas it is...
This is the output (with my own formatting text) :
(Polygon 20 is the polygon above)
But if you enlarged the square (10 times bigger in my test), the procedure answers my point is in the square.
So, I'm seeking for another algorithm, more precise.
Here is my VERTICE table, containing all vertices coordinates of each polygon of my DB
I need to check, for ALL polygons (there are a few thousands) if a given point passed in parameter is in a polygon (and if yes, which one(s)). I can do the loop by myself, but I miss a correct Point in polygon algorithm.
Could someone help me ?
Thank you very much.
SUMMARY
The corresponding SQL fiddle : http://sqlfiddle.com/#!3/0caa4/1
Your problem is that you've defined the polygon backwards. Let's explore this with the native SQL geography types
declare #s geography, #t geography, #p geography;
select #s = geography::STPolyFromText('POLYGON((45.97215 4.693909, 45.687 4.674683, 45.73302 5.460205, 46.05227 5.366821, 45.97215 4.693909))', 4326);
select #t = geography::STPolyFromText('POLYGON((46.05227 5.366821, 45.73302 5.460205, 45.687 4.674683, 45.97215 4.693909, 46.05227 5.366821))', 4326);
select #p = geography::STPointFromText('POINT(45.7664 4.87383)', 4326);
select #p.STIntersects(#s), #p.STIntersects(#t);
select #p.STBuffer(10), #s, #t;
As you can see, #s holds pretty much the whole world. In the result set viewer, if you zoom into where your "square" should be, you'll find a hole. Contrast that with #t which is the area that you expect. Also note that I ran this in SQL 2012 which improved on a limitation that existed pre-2012 that says that a geospatial instance can't cross a hemisphere boundary. If you run the above on a 2008 instance, you'll likely get an error to that effect for #s. Comment out the line defining #s and it'll run.
There's a "right-hand" rule when defining geo(graphy/metry) polygons. Imagine that you were in a car visiting the points in the order you've specified. The area that you're defining is what you'd see if you were looking out the right side of the car.
I am using SQL Server 2012. I have a table where I am tracking single point instances in a geography column. Storing them as a single point is working fine but I am trying to group some of them together into a new table where they would be a multipoint. I can get it working by inserting lat and long into a multipoint column like this:
DECLARE #g geography;
SET #g = geography::STMPointFromText('MULTIPOINT(-104.952784 39.524092, -104.935269 39.542652)', 4326);
INSERT INTO test(loc) values(#g)
What I want to do is select the values from a table that are already a geography data type. I am not sure if I can do this with a basic query or if I have to build it with a loop? I cannot seem to get it working either way.
Also, after I have that is there a method that will return me the center point of a multipoint column? I have been playing with some of the methods like STStartPoint and STEndpoint but I cannot seem to find a methods that return the center point?
Any help on these questions would be great and highly appreciated.
Thanks!
What you're looking for is the STCentroid() method but, unfortunately, it doesn't work for MultiPoint objects. I raised a Connect issue for this a few years back which has been closed by Microsoft as "Won't Fix", but you're welcome to vote it up anyway: https://connect.microsoft.com/SQLServer/feedback/details/588316/make-geometry-stcentroid-method-work-on-geometries-other-than-polygons
Meanwhile, you'll have to manually sum and then average the X and Y coordinate values individually to get the average "centre" of a Multipoint.
If I'm understanding your first question correctly, you have two points, stored individually as geography instances. If that's the case, you can use the STUnion method to combine them into one geography multipoint instance.