Develop Reference

Multiple Where clause in Android SQL statement

I am having some problem with the SQL statement for Android. Basically I have two where clause, bookID and userID and the SQL statement that I am having now:
public boolean updateLoan(String bookID, String userID, String currentDate) {
try {
ContentValues cv = new ContentValues();
cv.put("loanDate", currentDate);
mDb.update("loanBook", cv,
" bookID= '" + bookID + "'", null);
return true;
} catch (Exception ex) {
Log.e(TAG, ex.toString());
return false;
}
}
So I wonder how could I put two where clause in this method as currently I only can where clause by bookID. Do I simply put an "&" and continue the SQL statement?
Thanks in advance.

Do I simply put an "&" and continue the SQL statement?
Yes, use AND instead of &

Android SqlLite update last inserted row

This is what i am using for insert:
public long insert(String content, Date startAt, Date endAt) {
if (content == null || startAt == null) {
return 0;
}
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_CONTENT, content);
contentValues.put(KEY_START_AT, startAt.getTime());
if (endAt == null) {
contentValues.putNull(KEY_END_AT);
} else {
contentValues.put(KEY_END_AT, endAt.getTime());
}
return sqLiteDatabase.insert(TABLE_NAME, null, contentValues);
}
now i want to create update method which will update last inserted row. How can i get last inserted row?

If you have an id attribute that works as a primary key, you can do a raw database query on SqlLite.
Cursor cc = this.mDb.rawQuery("SELECT *" + " FROM " + "<Your DATABASE_NAME> " +
"ORDER BY id " + "DESC LIMIT 1", null);
return cc;
Here,
1. It returns a cursor.
2. mDb is a SQLiteDatabase class instance.
3. ORDER BY id allows the query to sort by id number. As I said, if you have an id as primary key in your table, your latest entry will have the maximum id number.
4. DESC allows to sort by descending order.
5. LIMIT 1 allows to return only 1 row.
6. Always be careful when writing raw queries, white spaces inside the query can be a lot of pain when you do not handle them carefully.
For further queries you can see this tutorial. And obviously Divya's answer is also a good one.

You can use a cursor to retrieve rows and say :
cursor.moveToLast();
OR
cursor.moveToPosition(cursor.getCount() - 1);

When you insert a row in to your table the insert query returns the key of the last inserted row. You can now use this key to update this row.
for example
int newInsertedKey = sqLiteDatabase.insert(TABLE_NAME, null, contentValues);
update table_name set column_name = 'Change 2' where columnID = newInsertedKey
An efficient method would be to avoid anymore database queries to get the last updated row.

Maybe he should use something like this
public long getLastId() {
Cursor c = mDb.query(currentTableName, new String[] { "MAX(_id)" },
null, null, null, null, null, null);
try{
c.moveToFirst();
long id = c.getLong(0);
return id;
}catch(Exception e){
return 0;
}
}
where _id is column by which you identify rows

Update doesn't work sqlite android

Having problem updating a column in a table. I tried both of these solutions:
this.openDataBase();
String SQLStatement = "update " + TABLE_POSES;
SQLStatement += " set " + COLUMN_SKIP + "=" + SKIP + " Where ";
SQLStatement += COLUMN_ID + "=" + String.valueOf(skipPoseId);
myDataBase.rawQuery(SQLStatement, null);
this.close();
and this:
this.openDataBase();
ContentValues args = new ContentValues();
args.put(COLUMN_SKIP,SKIP);
myDataBase.update(TABLE_POSES, args, COLUMN_ID + "=" + String.valueOf(skipPoseId),null);
this.close();
Neither of these code snippets work and I am not getting any exceptions thrown. What am I doing wrong?

You should use the second method using update() and you should check the return value. If the value is zero, then the state of the database isn't what you expect and no rows were updated. If the row is not zero then the updating is succeeding.
If anything is wrong with your accessing the database an exception will be thrown before the update() call.
I would take advantage of the args parameter of update() like so:
myDataBase.update(TABLE_POSES, args, COLUMN_ID + " = ?", new String[]{ Long.toString(skipPoseId) });

Use update like this,
String query="UPDATE tablename SET columnname="+var+ "where columnid="+var2;
sqlitedb.execSQL(query);
Just write your update query in String query and execute.

if you use db.begintransaction() in your code you must call db.setTransactionSuccessful() before db.endtransaction() such as:
try {
SQLHelper dbHelper = new SQLHelper(this);
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.beginTransaction();
...................
db.setTransactionSuccessful();
db.endTransaction();
db.close();
}
catch (Exception ex){
}

I had the exactly same issue. After much thought and debugging I saw that the WHERE condition wasn't addressing any rows of the table.
The odd thing is that the myDatabase.update command giving 1 as the return and I was understanding it as 1 row affected by the update.

Batch insert/update via contentProvider based on 2 fields

i'm creating a contentProvider , and i wish to be able to send it multiple DB records (contentValues) to be inserted or updated to a single table using a single batch operations .
how do i do that?
batchInsert is intended only for inserting , but wouldn't it mean that insertion of something that already exists won't do anything?
also , is there a way for the update operation to use a special constraint ? for example , i need to ignore the primary key and update based on 2 other fields that together are unique.

"batchInsert is intended only for inserting" : this is true BUT you can override it in your ContentProvider to perform an UPSERT (insert/update) depending on the URI passed to batchInsert.
The following is some working code that I currently use to perform bulk inserts on time-series data (admittedly, I just delete anything that gets in the way instead of updating, but you could easily change this to your own ends.).
Also note the use of the sql transaction; this speeds up the process immensely.
#Override
public int bulkInsert(Uri uri, ContentValues[] values) {
SQLiteDatabase sqlDB = database.getWritableDatabase();
switch (match(uri)) {
case ONEPROGRAMME:
String cid = uri.getLastPathSegment();
int insertCount = 0;
int len = values.length;
if (len > 0) {
long start = values[0].getAsLong(Programme.COLUMN_START);
long end = values[len - 1].getAsLong(Programme.COLUMN_END);
String where = Programme.COLUMN_CHANNEL + "=? AND " + Programme.COLUMN_START + ">=? AND "
+ Programme.COLUMN_END + "<=?";
String[] args = { cid, Long.toString(start), Long.toString(end) };
//TODO use a compiled statement ?
//SQLiteStatement stmt = sqlDB.compileStatement(INSERT)
sqlDB.beginTransaction();
try {
sqlDB.delete(tableName(PROGRAMME_TABLE), where, args);
for (ContentValues row : values) {
if (sqlDB.insert(tableName(PROGRAMME_TABLE), null, row) != -1L) {
insertCount++;
}
}
sqlDB.setTransactionSuccessful();
} finally {
sqlDB.endTransaction();
}
}
if (insertCount > 0)
getContext().getContentResolver().notifyChange(Resolver.PROGRAMME.uri, null);
return insertCount;
default:
throw new UnsupportedOperationException("Unsupported URI: " + uri);
}
}

Android: Deleting specific row in database

Sorry if this seems obvious. I'm trying to write a method to delete a row from a String showId. What would be the best way, and can Cursors only be used for Selects or also for Deletes and Updates?
These are the two methods I'm at so far:
public int deleteShowById1(String showId){
Cursor cursor = db.rawQuery("DELETE FROM tblShows WHERE showId = '" + showId+"'", null);
if (cursor.moveToFirst()) {
return 1;
} else
return -1;
}
public int deleteShowById2(String showId) {
String table_name = "tblShows";
String where = "showId='"+showId+"'";
return db.delete(table_name, where, null);
}

As we know from mysql query, it is same here in android.
String query = "DELETE FROM " +TABLE_NAME+ " WHERE " + COLUM_NAME+ " = " + "'"+VALUE +"'" ;
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL(query);
db.close();
VALUE may or may not have single quotation depending on datatype.

I tend to use the second method (db.delete), as I think using rawQuery is frowned upon.
If you do a select, then loop through the cursor to do updates or deletes, that would make sense, but to pass a cursor to do the delete or update doesn't make sense to me, as the program won't know how to parse the cursor results to get the correct fields.