Develop Reference

How to attach a database in Room?

I tried to attach database in Android Room like this: How to select from multiple databases in Android Room(How to attach databases) but i got error when building project:
error: There is a problem with the query: [SQLITE_ERROR] SQL error or missing database (no such table: database.table)
Error concerns
#Query("select t.id as tid from mydatabase.mytable t")
public List<MyPojo> getMyTableIds();
When I added #SkipQueryVerification, error changed on: error: Not sure how to convert a Cursor to this method's return type.
Error dissapears when I remove "mydatabase." from Query.
How to attach database in Android Room and make cross databases query?

You can attach your another database in onOpen callback. For details see the answer of another post here.

get database error code on SQLite exception in android

I use insertOrThrow in my android code to insert rows in to sqlite database. I use try catch to trap SQLiteException. I have set unique constraint in a column other than _id.
In case of errors i get exception message like the following and that is what i wanted.
"column word is not unique (code 19)"
Now, if the error is about duplicate insertion then i get the above error. And i would get messages like that for different errors.
What i need is an error number like in mysql. I was searching for a property of the android DB object which would have an error code but could not. I think in this case i need to parse the error message to get the error code.
The reason to have an error code is to identify the errors. In this case i can find duplicates if the error code is 19. If the entry is a duplicate then i will display 'Data already exists' message else i will display a generic error info like 'Unable to save information'.
Is there any other way to find the error code other than parsing?
Will the error code be consistent?

Android: SqliteDatabase's lastModified() is giving wrong value

I am using sqlcipher database. I am tracking the lastModified time of my database. According to my understanding long value returned by lastModified() function will change only if we update or add a value to the database we refer. I am using a query to fetch (not modifying) a value from the database, for this i am using the below code
mDatabaseFileObj = mContext.getDatabasePath("xxx.db");
Log.i(""," "+mDatabaseFileObj.lastModified());
mSQLiteDatabase = net.sqlcipher.database.SQLiteDatabase.openOrCreateDatabase(...)
Log.i(""," "+mDatabaseFileObj.lastModified());
mCursor = mSQLiteDatabase.rawQuery(query, null);
do{
....
}while(..)
In this i had printed two logs. First log before creation of mSQLiteDatabase obj and another log after that.According to the doc for lastModified() both the values printed by the logs should be same as i just quering not modifying the database. But the value is changing.
I couldnt sort out this problem.Give your thoughts on this.
An addtional info is, i had placed this code snippet in a function and i am calling that function 5 times and strangely for the first time alone the log is printing different values but for the rest 4 times the log printed values are same..
Thanks in Advance

Deepak,
openOrCreateDatabase is not a read only operation. In particular the wrapping library, which is based on the Android sqlite library, manipulates a table called android_metadata when the database is open. This could cause the timestamp to change, because the database is actually modified during open.

mDatabaseFileObj this is reference to your File object from OS don't confuse this with database in SQLITE database are implemented on top of file system only, so in first line you are printing when this file was last modified,
while second line you are trying to alter the file, and third line again printing time, so as per me and going with file systemn behaviour you will get a different time stamp, this doesn't mean if content inside this file was modified or not.
Just imagine it like this, open a txt file in windows and save it again without changing it notice time before and after they will be different.
Hope this help.

weird error comming from Android SQLite

I'm getting a weird error in DDMS, it appears just after the innocent "Finalizing a Cursor that has not been deactivated or closed", comming from my own DataAdapter (about that in next question)
Error:
"Finalizing a Cursor that has not been deactivated or closed. database = /data/data/net.toload.main/databases/lime, table = null, query = SELECT _id, code, code3r, word, score FROM mapping WHERE code3r = '0' AND code ='HTT' ORDER BY cod"
I didn't create any tables with such columns in my app! And my localdatabase isn't stored there... /databases/lime, but this error seems to come just after my real error from my own DataAdapter. I tried to pull the lime.db file to read the contents of the database but the pulled file is always of 0 bytes, though on DDMS-FileExplorer is much more, now 26624bytes.
So ... im thinking that maybe android/google is tracking my every move!! and the app doesnt run in a isolated process...
Anyway can you explain this error?

Your project must be using this Lime IME (Lightweight Input Method Editor):
http://code.google.com/p/limeime/

Problem while updating table in android

I created a table in the database that has the data like this:
Now i have written a query that updates the contact field by concatinating name and email fields:
UPDATE MyContacts SET contact=(SELECT name||'--'||email FROM MyContacts);
Here the problem is after executing the query the table is as below:
Why is it happening like this? In oracle i never faced this problem. Please help me. Thank you

Right now you're not specifying the correct row to retrieve the values from. Try something like this:
UPDATE MyContacts SET contact = name||'--'||email;
EDIT: Glad it worked. Your first issue was that your sub-select uses a SELECT statement with no WHERE clause (SELECT name||'--'||email FROM MyContacts will return 3 rows). One possible solution would be for SQLite to throw an error and say You've tried to set a column to the result of an expression that returns more than 1 row: I've seen this with MySQL and SQL Server. However, in this case SQLite appears to just use only the very first value returned. However, your second error then kicks in: since you don't narrow your UPDATE statement with a WHERE clause, it uses that first value returned to update EVERY single row, which is what you see.