Develop Reference

How to delete the rows from a table where a column contains a specific String?

As my title question, I want to delete some rows of table on SQLite where contains specific string.
Here are my methods I tried but there are no any row is deleted. I checked table of SQLite database by get it out and put in to DB Browser for SQLite which is downloaded from https://sqlitebrowser.org/
public void delete1(String table,String COLUMN,String link) {
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM "+table+" WHERE "+COLUMN+" LIKE "+link+"%");
}
public void delete2(String table,String name){
SQLiteDatabase db = this.getWritableDatabase();
db.delete(table, "PRODUCTNAME" + "LIKE ?", new String[]{name+"%"}) ;
}
Could you tell me how to do it or how have i to correct code ?

using db.delete(table, "PRODUCTNAME " + "LIKE ?", new String[]{name+"%"}) ; will only delete rows that start with the value in name.
Perhpas you want :-
db.delete(table, "PRODUCTNAME " + "LIKE ?", new String[]{"%"+name+"%"}) ;
Then it would delete rows that contain the value rather than start with the value.
With db.execSQL("DELETE FROM "+table+" WHERE "+COLUMN+" LIKE "+link+"%"); you need to enclose the string in single quotes and assuming that you want to delete a row that contains the value then use :-
db.execSQL("DELETE FROM "+table+" WHERE "+COLUMN+" LIKE '%"+link+"%'");
Using the delete convenience method (the first part) is the better option as it protects against SQL Injection, it properly encloses the value, builds the underlying SQL and also returns the number of affected (deleted) rows.
If you use the following, this will write dome debugging information that may assist in debugging :-
public void delete2(String table,String name){
SQLiteDatabase db = this.getWritableDatabase();
Log.d("DELETEINFO","Attempting to delete rows with \n\t->" + name);
int deletedCount = db.delete(table, "PRODUCTNAME " + "LIKE ?", new String[]{"%"+name+"%"}) >0) ;
Log.d("DELETEINFO","Deleted " + deletedCount + " rows.");
}

Updating rows in Android SQlite

I'm using SQlite in my Android app and the task is - how can I update all the rows in one table?
I have a 1st column with name "cl_id" (integer numbers 1-2-3-4..) and after deleting some rows, I wan't to make a cycle to fill this 1st column with a new values to keep them in right order.
I was trying to execute:
data.put("cl_id",index);
db.update("mdb_table_contactList", data, null, null);
but it's updates all the values in the first column :(

To update the field in specific row, try this;
ContentValues data = new ContentValues();
data.put("cl_id",index);
db.update("mdb_table_contactList", data, "id="+_id, null);
db.close();
It's good practice to have a primary key for each row data.
Here _id would be your primary key.

"just give rowId and type of data that is going to be update in ContentValues."
public void updateStatus(String id , int status){
SQLiteDatabase db = this.getWritableDatabase();
ContentValues data = new ContentValues();
data.put("status", status);
db.update(TableName, data, "columnName" + " = "+id , null);
}

Try this it must work
void updateDatail(String id) {
ContentValues data = new ContentValues();
data.put("cl_id",index);
db.update("mdb_table_contactList", data, "id=?", new String[]{id});
db.close();
}

How can use sqlite update via ContentValues when want to update depend on current value and how can retrieve the Result?

I've a situation in sqlite that make you an example: My table has two fields,"_id" and "_score" . I have a record with _id=1, _score=10. I want to update this row to 5 number more than the current value(10). in SQL i can do it simple like:
Update my_table set _score = _score + 5 where _id = 1
but in sqlite I have these that I don't know how can fix it to what I want :
ContentValues values = new ContentValues();
values.put("_score", my_value);
SQLiteDatabase db = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null, SQLiteDatabase.OPEN_READWRITE);
int id = db.update(MY_TABLE,values,"_id = ?",new String[]{String.valueOf(my_id)});
and the Other problem is the returned value. I think in above example I give
id = 1
for 1 row effected. but I want to know that: Is there any way to retrieve the value of updated column(in my example I want to give "15"). Some thing like in SQL server that we fetch from
"##ROWCOUNT" or "##fetch_status"
Hope to describe it well. thanks.

Android's update() function can set only fixed values.
To execute your SQL statement, you have to use execSQL():
db.execSQL("Update my_table set _score = _score + 5 where _id = 1");
In SQLite, the UPDATE statement does not return any data (except the count of affected rows). To get the old or new data, you have to execute a SELECT separately.

For your first problem about updating the score value try this:
ContentValues values = new ContentValues();
values.put("_score", my_value);
SQLiteDatabase db = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null, SQLiteDatabase.OPEN_READWRITE);
int id = db.update(my_table, values, _id + " = ?",
new String[] { String.valueOf(my_id) });
}

How to Use ContentValues and SQLiteOpenHelper to modify sqlite database in Android?

I wrote a rssFeedReader Application and use directly sqliteSyntax to modify database.
this is my code:
database.execSQL database= openOrCreateDatabase("MyDB", MODE_PRIVATE, null);
database.execSQL("Create TABLE IF NOT EXISTS Press (press_name
VARCHAR, press_url VARCHAR");
database.execSQL("INSERT INTO Press VALUES ('Tasnim',
'http://www.tasnimnews.com/english/rss/feed/?d=2&c=1&m=6&alt=Recent%20News');");
database.execSQL("UPDATE Press press_name ='Tasnim',
press_url ='http://www.tasnimnews.com/english/rss/feed/?
d=2&c=1&m=6&alt=Recent%20News');");
Cursor cursor = database.rawQuery("SELECT * FROM MyTable", null);
database.close();
and now my question is how can I migrate to SQLiteOpenHelper and ConentValues method to modify database.

// Gets the data repository in write mode
SQLiteDatabase db = mDbHelper.getWritableDatabase();
// Create a new map of values, where column names are the keys
ContentValues values = new ContentValues();
values.put(FeedEntry.COLUMN_NAME_ENTRY_ID, id);
values.put(FeedEntry.COLUMN_NAME_TITLE, title);
values.put(FeedEntry.COLUMN_NAME_CONTENT, content);
// Insert the new row, returning the primary key value of the new row
long newRowId;
newRowId = db.insert(
FeedEntry.TABLE_NAME,
FeedEntry.COLUMN_NAME_NULLABLE,
values);
You can find it here http://developer.android.com/training/basics/data-storage/databases.html

Update value to specific primary key in sqlite , android?

I have to below table structure of my sqlite database in android
I want to update value to "answer" column according to the ques id.
How do I do it?
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_Answer, answer);
// Inserting Row
db.insert(TABLE_Question, null, values);
db.close(); // Closing database connection

I want to insert value to "answer" column according to the ques id.
This operation called "update" instead of "insert".
insert: means to add new record in table,
update: means change value of any exist row columns
so required operation is update.use update method as:
String where = "Ques_id=?";
String[] whereArgs = new String[] {String.valueOf(Ques_id)};
ContentValues values = new ContentValues();
values.put(KEY_Answer, answer);
db.update(TABLE_Question, values, where, whereArgs);

insert() inserts a new row. To update a column on an existing row, use update() with a selection like "Ques_id=" + id.