Develop Reference

unable to retrieve data of column from database

I am having a table named keywords in database.I want to retrieve data of alarm and location columns from this table and unable to retrieve them except for contact number.For now I am showing their values in a Toast but every time I run any query to show my alarm or location in Toast its empty.But my contact_number is always shown.Don't understand the cause of this problem .I have also checked my tables view and it is showing the values of alarm ,location in them.
Create Table keywords( contact_number text primary key , alarm text , location text )
and my insert function is
public boolean insertkeys (String alarm ,String location ,String contact){
SQLiteDatabase db = this.getWritableDatabase();
//ContentValues is a name value pair, used to insert or update values into database tables.
// ContentValues object will be passed to SQLiteDataBase objects insert() and update() functions.
// ContentValues contentValues = new ContentValues();
ContentValues contentValues = new ContentValues();
contentValues.put("alarm",alarm);
contentValues.put("location",location);
contentValues.put("contact_number",contact);
long ins = db.insert("keywords",null,contentValues);
long upd = db.update("keywords",contentValues,"contact_number = ?",new String[]{contact});
// db.close();
if(ins == -1 && upd == -1)
return false;
else
return true;
}
I am inserting plus updating my data every single time my save button is clicked.Can anyone here tell how can I write a query to retrieve data of these fields and set it to Toast or Edit text. I am new to Database and stuck here for about a week. Thanks in advance for help :)

You extract data via a SELECT query which is returned as a Cursor when using the Android SDK.
The Cursor is similar to a table in that it has a number of rows, each with a set number of columns as determined by what you select.
To get all rows the SELECT query would be along the lines of :-
`SELECT * FROM keywords`
To do this using the Android SDK you could use the SQLiteDatabase query convenience method e.g. for the above you could use :-
Cursor cursor = db.query("keywords",null,null,null,null,null,null);
check the links above for the values/parameters that can be passed and how they correlate with the SELECT statement.
You then traverse the returned cursor extracting the data, typically using the Cursor's move??? methods. Noting that most will return false if the move could not be made and also noting that the original position in the Cursor is before the first row
As such you could have a method that returns a Cursor as per :-
public Cursor getAllKeys(){
SQLiteDatabase db = this.getWritableDatabase();
return db.query("keywords",null,null,null,null,null,null);
}
You could then process all the rows using :-
Cursor csr = yourDBHelper.getAllKeys();
while (csr.moveToNext()) {
String current_contact_number = csr.getString(csr.getColumnIndex("contact_number");
String current_alarm = csr.getString(csr.getColumnIndex("alarm");
String current_location = csr.getString(csr.getColumnIndex("location"));
...... your code to Toast or use the retrieved values
}
csr.close(); //<<<<<<<<<< you should always close a Cursor when finished with it.
Additional
In regard to the comment :-
Cursor query which you have suggested I tried to make changes in it
like putting column and where clause but after that it returns me
nothing when I execute it.Could you tell me that query too.
The following could be a method to retrieve just the alarm according to a contact number.
public String getAlarmByContactNumber(String contactNumber){
String rv = "";
SQLiteDatabase db = this.getWritableDatabase();
Cursor csr = db.query(
"keywords", //<<<<<<<<<<<< the FROM clause (less the FROM keyword) typically the name of the table from which the data is to be extracted (but can include JOINS for example, for more complex queries)
new String[]{"alarm"}, //<<<<<<<<<< A String[] of the column names to be extracted (null equates to * which means all columns) (note can be more complex and include functions/sub queries)
"contact_number=?", //<<<<<<<<<< WHERE clause (less the WHERE keyword) note **?** are place holders for parameters passed as 4th argument
new String[]{contactNumber},
null, //<<<<<<<<<< GROUP BY clause (less the GROUP BY keywords)
null, //<<<<<<<<<< HAVING clause (less the HAVING keyword)
null //<<<<<<<<<< ORDER BY clause (less the ORDER BY keywords)
);
if (csr.moveToFirst()) {
rv = csr.getString(csr.getColumnIndex("alarm"));
}
csr.close();
return rv;
}
The above assumes that you would only have/want one alarm per contact number.
The above is in-principle code, it has not been run or tested and may therefore contain some minor errors.

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();
}

getContentResolver() Returns all rows of table and updates none

I am using following statement to update a row in the Content provider's table.
ContentValues values = new ContentValues();
values.put(ReminderData.REMINDERS_STATUS, Boolean.valueOf(isChecked));
mCtx.getContentResolver().update(ReminderData.CONTENT_URI, values, ReminderData._ID + "=?", new String[]{cursor.getString(cursor.getColumnIndex(ReminderData._ID))});
Values:
ReminderData.CONTENT_URI : content://com.android.firstapp.data/reminder
cursor.getString(cursor.getColumnIndex(ReminderData._ID)) : 2
I always get the result as 0, i.e. 0 rows updated. But I have a row in the table with id 2.
Also when I try to retrieve a row from the content provider using below code:
Cursor cursor = getContentResolver().query(ReminderData.CONTENT_URI, null, ReminderData._ID+"=?", new String[] {id+""}, null);\
id value is 3.
But I get all the rows in the cursor with cursor count as 5.
I don't know what is the issue. Please help. TIA.

Android Sqlite update between

I want to update my table data base on _id between range like 120 to 150. How can I update data using update or how can I do it ?

you can use the following code :-
ContentValues cv = new ContentValues();
cv.put("Field1","Bob"); //These Fields should be your String values of actual column names
cv.put("Field2","19");
cv.put("Field2","Male");
myDB.update(TableName, cv, "_id>=120 and _id<=150", null);

Update singel cell of a row in an SQLite database on Android

I wont to update a single cell of a row in the database. However the row contains of 5 columns so and i would like to not passing all the other values as well as they should remain the same.
I have this code snippet:
Cursor cursor = db.query(STATION_TABLE, null, null, null, null, null, null);
//If the database already include some stations.
if(cursor.moveToFirst())
{
ContentValues stationValues = new ContentValues();
for(StopLocation station: stations)
{
stationValues.clear();
//The database already includes the station
if(cursor.getString(POS_STA_ID).equals(station.getId()))
{
values.put(KEY_STA_DISTANCE, "null");
db.update(STATION_TABLE, stationValues, KEY_STA_ID + "=?", new String[]{station.getId()});
}
The db.update method throws this exception:
java.lang.IllegalArgumentException: Empty values
Any ideas on how to solve this?

If I understand the question correctly and assuming you are always dealing with one row, there are two possible ways to approach this:
First:
Get the values of all fields in the entire row, and declare them as content values before updating:
ContentValues cv = new ContentValues();
cv.put("Field1","123");
cv.put("Field2","True")
Second:
Use execSQL() method:
String strSQL = "UPDATE your_table SET Field1 = foo WHERE POST_STA_ID = "+ station.getId();
myDataBase.execSQL(strSQL);