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Wednesday, January 29, 2020

Importing .shp (shape) GIS files into mySQL db

Steps to import SHP files exported from GIS systems, into mySQL db:

To import GIS data into mySQL, we need to translate the geometry GIS descriptions into sql statements.
This can be achieved by using the opensource shp2mysql utility, along with cygwin1.dll (both in the same folter)

After generating the .sql file, all is left to do is to import it into mysql. I did it using sqlyog: right click in the target database → Import → Execute SQL Script → select the .sql file generated above.

But before doing that, you might do the following:

The table name where the data will be imported is derived from the sql output file name. Make sure you rename it in the Create Table statement, accordingly.

I had to manually fix the .sql file, to overcome the following issues:

  1. shp2mysql will create two columns named ID. I renamed the 2nd one to _ID
  2. my shp2mysql execution generates a 3D representation of each point, and I did not find a 3D syntax for MULTILINESTRING. I ended up replacing all 0.000000000000000 occurrences in the sql file to blank spaces, to fix it.
  3. the generated sql file had a -1 SRS id for each generated gis representation in WKT. mySql stated -1 is invalid, we checked which SRS id was used in our other GIS dbs, figured out it was 0, then I replaced all occurrences of ,-1) with ,0) in my sql file.
  4. shp2mysql will generate the sql file using a deprecated mysql function, GeometryFromText. According to mysql documentation, it was deprecated in mySql 5.7.6. Since my machine has mySql 8, I renamed all occurrences of it to ST_GeomFromText:

GeomFromText() and GeometryFromText() are deprecated as of MySQL 5.7.6 and will be removed in a future MySQL release. Use ST_GeomFromText() and ST_GeometryFromText() instead.

Now the file is valid and free of errors, and you can proceed and run the Execute SQL Script described above.

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