Develop Reference

SQLite set field to same value as generated id at insert

We have a requirement where some fields in a table need to have the same value as their ID. Unfortunately, we currently have to insert a new record and then, if needed, run another update to set the duplicate field (ID_2) value to equal the ID.
Here is the Android Sqlite code:
mDb.beginTransaction();
// ... setting various fields here ...
ContentValues contentValues = new ContentValues();
contentValues.put(NAME, obj.getName());
// now insert the record
long objId = mDb.insert(TABLE_NAME, null, contentValues);
obj.setId(objId);
// id2 needs to be the same as id:
obj.setId2(objId);
// but we need to persist it so we update it in a SECOND call
StringBuilder query = new StringBuilder();
query.append("update " + TABLE_NAME);
query.append(" set " + ID_2 + "=" + objId);
query.append(" where " + ID + "=" + objId);
mDb.execSQL(query.toString());
mDb.setTransactionSuccessful();
As you can see, we are making a second call to set ID_2 to the same value of ID. Is there any way to set it at INSERT time and avoid the second call to the DB?
Update:
The ID is defined as follows:
ID + " INTEGER PRIMARY KEY NOT NULL ," +

The algorithm used for autoincrementing columns is documented, so you could implement it manually in your code, and then use the new value for the INSERT.

This is quite a ugly hack, but it may be possible :
with id_table as (
select coalesce(max(seq), 0) + 1 as id_column
from sqlite_sequence
where name = 'MY_TABLE'
)
insert into MY_TABLE(ID_1, ID_2, SOME, OTHER, COLUMNS)
select id_column, id_column, 'SOME', 'OTHER', 'VALUES'
from id_table
It only works if the table ID is an AUTOINCREMENT, and is therefore managed via the documented sqlite_sequence table.
I also have no idea what happen in case of concurrent executions.

You could use an AFTER INSERT TRIGGER e.g.
Create your table (at least for this example) so that ID_2 is defined as INTEGER DEFAULT -1 (0 or any negative value would be ok)
e.g. CREATE TABLE IF NOT EXISTS triggertest (_id INTEGER PRIMARY KEY ,name TEXT ,id_2 INTEGER DEFAULT -1);
Then you could use something like (perhaps when straight after the table is created, perhaps create it just before it's to be used and drop it after done with it ) :-
CREATE TRIGGER triggertesting001
AFTER INSERT ON triggertest
BEGIN
UPDATE triggertest SET id_2 = `_id`
WHERE id_2 = -1;
END;
Drop using DROP TRIGGER IF EXISTS triggertesting001;
Example usage (testing):-
INSERT INTO triggertest (name) VALUES('Fred');
INSERT INTO triggertest (name) VALUES('Bert');
INSERT INTO triggertest (name) VALUES('Harry');
Result 1 :-
Result 2 (trigger dropped inserts run again ):-
Result 3 (created trigger) same as above.
Result 4 (ran inserts for 3rd time) catch up i.e. 6 rows updated id_2 with _id.
I'd strongly suggest reading SQL As Understood By SQLite - CREATE TRIGGER
Alternative solution
An alternative approach could be to simply use :-
Before starting transaction, retrieve mynextid from table described below
ContentValues contentValues = new ContentValues();
contentValues.put(ID,mynextid);
contentvalues.put(ID_2,mynextid++);
contentValues.put(NAME, obj.getName());
Then at end of the transactions update/store the value of mynextid in a simple single column, single row table.
i.e. you are managing the id's (not too dissimilar to how SQLite manages id's when 'AUTOINCREMENT' is specified)

If table already exists do not insert rows and give toast

I have an app that allows the user to save some chosen rows from a temporary table. The user is able to name the new table.
I am successfully creating a table using the name the user has input, and putting all the chosen rows from the temporary table into the new table.
However, if the table name they enter already exists, I want to notify them via Toast and have them choose another name. I am still learning sqlite - is there a way to do this?
In my head I am using some sort of if statement to check if the table exists, and then executing code, however half of it is in sqlite and half is in java. I'm not sure the correct way to do this. Any suggestions are greatly appreciated!
private void createTable() {
dbHandler.getWritableDatabase().execSQL("CREATE TABLE IF NOT EXISTS " + favoriteName + " ( _id INTEGER PRIMARY KEY AUTOINCREMENT , exercise TEXT , bodypart TEXT , equip TEXT );");
dbHandler.getWritableDatabase().execSQL("INSERT INTO " + favoriteName + " SELECT * FROM randomlypicked");

Try
Cursor cursor = dbHandler.getReadableDatabase().rawQuery("select DISTINCT tbl_name from sqlite_master where tbl_name = '"+tableName +"'", null);
if(cursor!=null) {
if(cursor.getCount()>0) { //table already exists
//show toast
cursor.close();
return;
}
cursor.close();
}
//create table and insert normally

android second column returns no value

I have a problem to create a table. If I try to get a value from the second column, android writes a empty space in the toast. But if I try to get a value from the first column, android writes the value of the column correctly. The query functions to write the first column and to write the second column are equal. So I think the Creation of the Table is the problem. But look yourself:
public SQLiteDatabase tabelleerstellen(){
SQLiteDatabase leveldatabase = openOrCreateDatabase("leveldata.db",SQLiteDatabase.CREATE_IF_NECESSARY, null);
leveldatabase.setVersion(1);
final String CREATE_TABLE_LEVEL =
"CREATE TABLE IF NOT EXISTS tbl_level ("
+ "id INTEGER PRIMARY KEY AUTOINCREMENT, "
+ "ME1 TEXT, "
+ "ME2 TEXT, "
+ "ME3 TEXT, "
+ "ME4 TEXT, "
+ "ME5 TEXT, "
+ "ME6 TEXT, "
+ "ME8 TEXT, "
+ "GESCHAFFT INTEGER);";
leveldatabase.execSQL(CREATE_TABLE_LEVEL);
return leveldatabase;
}
public void tester(SQLiteDatabase leveldata){
ContentValues cursortester = new ContentValues();
cursortester.put("ME2","25");
leveldata.insert("tbl_level",null,cursortester);
String[] testerpr = {"ME2"};
Cursor testerprüfen = leveldata.query("tbl_level",testerpr,null,null, null, null,null,null);
testerprüfen.moveToFirst();
String dada = testerprüfen.getString(testerprüfen.getColumnIndex("ME2"));
Toast testertoast = Toast.makeText(getApplicationContext(),dada,Toast.LENGTH_SHORT);
testertoast.show();
}

Please check the following things:
Please make sure the table is up to date .. so try to call DROP TABLE IF EXISTS tbl_level; and recreate the table.
If you run a test make sure the table is completely empty ... so delete everything at the beggining of the test.
If the table can contain elements during the test then make sure you check the last inserted element. Please note that calling testerprüfen.moveToFirst(); moves the cursor to the first row in the table so checking that row every time is even if the table contains 50 elements is not a good thing. In this case you either use a sorting option in your query of uese while (testerprüfen != null && testerprüfen.moveToNext()) {// Your code here}
All in all I think your problem is that you already inserted more that one element in the able but you always check only the first element (with testerprüfen.moveToFirst();). Please not that there is a cursor.moveToLast() method that you can also call. This method moves the cursor to the last row in the table.

How do I delete the last row of a SQLite table in Android. I don't have an _id column

Okay, so I have a high score table. I have two columns, Player name and score..
Every time a new score is to be added to the table I delete the last row, put the new score and new player name in the last row and then sort the table according to the score.
I can't delete the row with minimum score because there might be multiple entries with the same score and I don't want to delete all of them.

You might want to rebuild your table and include an id column with integer primary key autoincrement. You can do quite a bit with that column in place (here's an SO question you can look into for that).
Anyway I don't know how your process goes and why you need to delete the last row but here's an example of using an ID column to get the last row ( which I assume would be the latest insert and is what usually happens if you declare an ID integer primary key autoincrement column):
public int LastInsert() {
SQLiteDatabase db = this.getReadableDatabase();
final String MY_QUERY = "SELECT MAX(" + colID + ") FROM " + myTable;
Cursor cur = db.rawQuery(MY_QUERY, null);
cur.moveToFirst();
int ID = cur.getInt(0);
cur.close();
return ID;
}
From here you can probably just get the result of LastInsert and use that to direct what your delete function should delete.
Imo you're better of maybe just updating the last row instead of deleting and reinserting in it's place though. Something like this :
public int UpdateAcc(Account acc) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(colName, acc.getName());
cv.put(colScore, acc.getScore());
return db.update(myTable, cv, colID + "=?", new String[]{params});
}

I don't remember rather android with sqlite supports multiple commands per statement, but if so this might work:
DELIMITER ;;
SET #LastId = (SELECT ROWID FROM yourTable ORDER BY ROWID DESC LIMIT 1);;
DELETE FROM yourTable WHERE ROWID=#LastId;;
Otherwise you can store this in a integer variable:
SELECT ROWID FROM yourtable ORDER BY ROWID DESC LIMIT 1;
Then use that variable to run the next line
DELETE FROM yourtable WHERE ROWID=#ThatIntegerHere;

Get id(s) after applying batch operation

I am applying a batch of ContentProviderOperations on my provider:
ContentProviderResult[] result = resolver.applyBatch(...)
Everything works as expected the data is being inserted into the DB, but if I want to extract the id(s) the last element of the uri which should be the id is always null.
Is this happening because I have set the _id of the table to autoincrement (in other words would it work if I am not autoincrementing the id and fill it with a manually uid from my code).
If not, can anyone tell me whats causing this behavior.
Update: This is the String for creating the table:
private static final String CREATE_TABLE_WORKFLOWSTATES =
"CREATE TABLE " + Tables.WORKFLOWSTATES + " ("
+ BaseColumns._ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ WorkflowStatesColumns.NAME + " TEXT NOT NULL,"
+ "UNIQUE ("+ WorkflowStatesColumns.NAME + ") ON CONFLICT IGNORE)";
and if i view the table I can see the columns _id and name, the inserted data that is visible shows that the autoincrement works properly.
Update 2: This is how I have build the ContentProviderOperation:
this is my ArrayList with ContentProviderOperations (CollectionUtils is a custom class in order to instantiate the Arraylist):
ArrayList<ContentProviderOperation> batch = CollectionUtils.newArrayList();
and this is the actual operation:
batch.add(ContentProviderOperation
.newInsert(InvoiceContract.addCallerIsSyncAdapterParameter(WorkflowStates.CONTENT_URI))
.withValue(WorkflowStates.NAME, task.getWFS()).build());

In case of insertion (and I guess that you insert a row into your database), the result[i].uri contains URI of a newly inserted row, where i is the index of the corresponding operation in operations array. Try to print this URI and you'll see if it corresponds to real id.
If one of your operation is UPDATE or DELETE the corresponding result URI will be null, but result[i].count will contain the number of updated/deleted rows.
UPDATE
I guess the problem is that you have a unique index on NAME. Maybe, you have a row already inserted with the same name?
UPDATE2
The problem was that the insert function in the ContentProvider did not return the id correctly.