1

I want to calculate the MBR for the column of table.

I have already install Postgis and postgresql.

the data is cvs enter image description here

and I load the data to my postgresql-table by [copy]

and my table scheme is enter image description here

and When I running

SELECT ST_Envelope (wkb_geometry::geometry) from test1;

OR running

SELECT PostGIS_ADDBBox(wek_geometry) from test1;

the shell prompt me

ERROR:Invalid endian flag value encountered.

I just want to create the Minimum bounding box(MBR) to my table(by postgis,and using web_geometry column),but I don't know what should I using the function and what the correct syntax

1

If i read it correct you import a WKT and then you try to cast wkb_geometry to geometry. You picture shows a text file with WKT and fields of your table called wkb_geometry. How do you imported the data? Either you have a real binary field where you threw in text or your field has a different name compared to its content.

WKT and WKB are completly different things, you can´t mix them. One is stored as text the other as binary format. Therefore different tools are needed. I don´t think that the normal cast function will work here anyway, as this is a postgresql standard function and has nothing to do with geometries, you need the PostGIS functions. If you really have a WKB you need the function ST_GeomFromWKB.

Select ST_Envelope(StGeomfromWKB(your field, your coordinate reference as srid))

Or for WKT you go with STGeomFromText:

SELECT ST_Envelope(STGeomFromText(your field, your coordinate reference as srid))
  • I load the data by ogr2ogr(.shp -----> .csv ) and when I running Select ST_Envelope(St_GeomFromWKB(wkb_geometry, 4326)) from test1; The prompt: ERROR: Invalid endian flag value encountered. and when I running: SELECT wkb_geometry From test1 where fnode_=1; the web_geometry is \x4c494e45535452494e4720283132312e32393636373932373136333234‌​39392033312e38353239‌​34383130313631323438‌​2c3132312e3239353838‌​333137383731 > 3039382033312e38343933353536393736333137393729 – user82538 Sep 14 '16 at 11:58
  • and when I running:` Select ST_GeomFromText(wkb_geometry,0) from test1;` the prompt > ERROR: function st_geomfromtext(bytea, integer) does not exist LINE > 1: Select ST_GeomFromText(wkb_geometry,0) from test1; > ^ HINT: No function matches the given name and argument types. You might need to add explicit type casts. I have already don't know what the wkb_geometry format – – user82538 Sep 14 '16 at 11:59
  • How did you bring the .csv into the database? Because it has WKT as geometry format and your column wkb. I guess that the error lies there. When you import the csv you need to have the same columns. Lets test the following: Create a new table with all columns named like the ones in your .csv file. The WKT-Column as text. Then COPY new_table FROM "file" . The copy command needs the same amount of columns in the input and output table. Try your query with the new table. – Matte Sep 14 '16 at 13:18
  • yep,I know use COPY should have same column, first I using ogr2ogr load the table(new table,named test),and I go to 【pgAdmin】to see the SQL of the table scheme. And I create new table(named test1) column and create column the same as the test. So I think the table(test1) have the same column .(Because the next step I want to using cities,so I must create new table) – user82538 Sep 15 '16 at 0:39
  • I already run CREATE table test2( WKT text,fnode_ integer,tnode_ integer,lpoly_ integer,rpoly_ integer,length double precision,riverf_ integer,riverf_id integer,code integer,gb integer,hydc text,tn integer,name text); and COPY test2 FROM '/home/pj/Desktop/test1.csv' CSV header; but prompt error: ERROR: extra data after last expected column CONTEXT: COPY test2, line 2: ""LINESTRING (121.28987121582 31.852741241455099,121.286529541015994 31.8526306152344,121.28036499023..." – user82538 Sep 15 '16 at 1:49

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