Update: SQLite 2021-03-12 (3.35.0) now supports DROP COLUMN. From: http://www.sqlite.org/faq.html: (11) How do I add or delete columns from an existing table in SQLite. SQLite has limited ALTER TABLE support that you can use to add a column to the end of a table or to change the name of a table. If you want … Read more
XCode 4 (final) seems to be inconsistent. Using one argument works on the device, but fails in the simulator: -com.apple.CoreData.SQLDebug 1 Using two arguments works on the device and in the simulator: -com.apple.CoreData.SQLDebug 1
Sure you can. The docs are a little conflicting about this as they also say that no limitations are imposed. I think they should say that relative paths are to the above location and dbs there ARE private. Here is the code you want: File dbfile = new File(“/sdcard/mydb.sqlite” ); SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile, null); … Read more
As you’ve read Core Data vs SQLite 3, you know that Core Data and the persistence mechanism (SQLite in this case) are largely orthogonal. Core Data is really about managing an object graph and it’s main use case is for the model component of an MVC architecture. If your application fits nicely into this architecture, … Read more
try this way select (select count() from XXX) as count, * from XXX;
Finally figured this out from this post. The PRAGMA foreign_key setting does not persist but you can set it every time the connection is made in the ConnectionString. This allows you to use Visual Studio’s table adapters. Make sure you have the latest version (1.0.73.0) of system.data.sqlite installed (1.0.66.0 will not work). Change your ConnectionString … Read more
For MS SQL Server: SCOPE_IDENTITY() will return you the last generated identity value within your current scope: SELECT SCOPE_IDENTITY() AS NewID
Solving the issue using an emulator The folder /data can be empty because you are missing the proper permissions. To solve it, I had to execute the following commands. adb shell su Those commands starts a shell in the emulator and grant you root rights. The command adb is located in the folder platform-tools of … Read more
I don’t know of any performance penalties in frequent closing/opening of the database (regardless of its size). I think the answer to this question also depends on what type of application is accessing the database. Do you “re-query” the database a lot? Then it seems rectified to keep it open. Do you fetch different data … Read more
Make it INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL. Here’s what the docs say: If a column has the type INTEGER PRIMARY KEY AUTOINCREMENT then… the ROWID chosen for the new row is at least one larger than the largest ROWID that has ever before existed in that same table. The behavior implemented by the AUTOINCREMENT … Read more