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androidsqlitepragma

Detect if a table contains a column in Android/sqlite

So I have an app on the market, and with an update I want to add some columns to the database. No problems so far. But I want to detect if the database in use is missing these columns, and add them if this is the case. I need this to be done dynamically and not just after the update to the new version, because the application is supposed to still be able to import older databases. Normally I would be able to use the PRAGMA query, but Im not sure how to do this with Android. I cant use execSQL since it is a query, and I cant figure out how to use PRAGMA with the query()-function.

Ofcourse I could just catch exceptions and then add the column, or always add the columns to each table before I start to work with it, but that is not a neat solution.

Cheers,

Solution

  • Pragma works. As an example I just tried it on one of my Android App DBs. 

    sqlite> pragma table_info (userCommand);

cid name        type    notnull     dflt_value  pk
0   id      INTEGER     0       1
1   description TEXT    0       0
2   message     TEXT    0       0

    As we can see there are three fields in the specified table. id, description, and message.

    So in your app, use something like: 

    Cursor c = null;
c = RawQuery ("pragma table_info (userCommand)",null); 
// if c has records and is not null then iterate through the records in search of your table name.

    Please excuse the poor formatting.