v.db.join and "duplicate column name"

[lucadelu]

Today I found a problem when I try to join tables with v.db.join. The problem was that the key columns have the same name and the join returned an error.

v.db.join map=confini_provinciali column=PROV otable=tabprovince ocol=PROV

DBMI-SQLite driver error:
Error in sqlite3_prepare():
duplicate column name: PROV

ERROR: Error while executing: 'ALTER TABLE confini_provinciali ADD COLUMN
       PROV CHARACTER
       '
ERROR: Cannot continue (problem adding column).
ERROR: Cannot continue.

To solve this problem I adding two flag that they permit to pass it. One permit to not copy the join column, the data of join column are already present on the map table; the other flag permit to copy all the column from other_table adding "_o" to the columns name. This is the idea used by v.overlay that add "_a" at the columns of ainput and "_b" for the columns of binput. In attachment you can found the patch, test it and if you think that it's a good solution please add it to the svn

[lucadelu]

sorry the patch before was wrong

[mlennert]

I'm attaching a patch to the current Python version of v.db.join that does the following:

• add a 'column_prefix' parameter that allows defining a column prefix for all newly joined columns in order to avoid any column name conflicts

• never join the key column from the other table as that would be redundant

Any objections against applying this ?

[neteler]

Ticket retargeted after milestone closed

[neteler]

Ticket retargeted after milestone closed

[neteler]

Ticket retargeted after milestone closed