Develop Reference

How to fix empty string while fetching it from Database?

I am fetching a string from Database using the column id. When I enter a query in SQLite DB Browser it returns what is need but the same query returns nothing when coded through Java.
My Data Base contains a table named drugs which has 3 columns i.e. drug_id, drug_name and drug_overview. Using drug_id i am fetching drug_overview. I have tried the query in db browser which returns me the correct string from drug_overview but the same query returns nothing when coded through java.
SQLite DB Browser query:
SELECT * FROM drugs Where drug_id = 50;
JAVA CODE:
String query105 = "SELECT * FROM drugs Where drug_id = " + drug_id;
Log.e("TESTDB1","Drugs table query: " + query105);
Cursor c105 = db.rawQuery(query105,null);
if (c105 != null){
while (c105.moveToNext()){
String overview = c105.getString(c105.getColumnIndexOrThrow("drug_overview"));
Log.e("TESTDB1","Overview: " + overview);
}
c105.close();
}
Expected result is Overview: Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus in the body. It will not cure herpes, but it can lessen the symptoms of the infection.Acyclovir is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox, as well as varicella (chickenpox), and cytomegalovirus.Acyclovir may also be used for purposes not listed in this medication guide.
But the actual result is Overview:
empty
. When i change the id in my query it gives the correct result from a different drug.

I am afraid that your problem may be with the actual data itself as Mike said in comment, I think your database in the files is old and you haven't copied the latest to folder. Try to re-install and delete old database

Your query returns 0 or 1 lines so I think you should use c105.moveToFirst() instead of c105.moveToNext(). moveToNext is supposed to be used for a list, not for a single entry. Do something like:
if (c105.moveToFirst()){
String overview = c105.getString(c105.getColumnIndex("drug_overview"));
// do something with the result
}
c105.close();

Is this way of fetching data from sqlite correct?

I am using this query to fetch data from sqlite but only one condition is working but not two at same time.
I am also getting some notification that no such column but it exist.
String lquery = "SELECT SUM(totalcalorie) AS LTotal FROM fooditem
WHERE name = ('" + fname + "') AND foodtype = 'Lunch'";

you might be having null values on those places which you are checking while calling..
go through your code again queries seems write.

change totalcalorie to INTEGER type in the database schema
comment says that you are using TEXT

android: SQLite query returns no results

I am building an Android app that uses a SQLite database.
For this one task I have to run a query that looks like this:
SELECT item.id, item.price, t1.quantity
FROM item, (SELECT id, price
FROM list
WHERE list.state = 'sold') t1
WHERE item.id = t1.id
So far, I have tried:
Cursor c = resolver.query(uriRawQuery, null, selection, null, null)
where uriRawQuery is used to tell the ContentProvider that it should perform a db.rawQuery(selection, null) and selection is a string similar to the query above.
The problem is no data is returned into the Cursor. When I call c.moveToFirst() I get false.
The weird thing is that if I open the database file in SQLite Manager and run the exact same query I get results.
I know I can modify the query to make a join between the original list and item tables but I find it to be less efficient that way.
Any ideas would be very appreciated as I have spent too man hours on this already.
EDIT
I know what a join is, what I said is that it is a lot more efficient if I do it like this instead of using the entire list table.
I forgot a very important aspect
The WHERE clause looks like
" WHERE list.state = 'sold' and list.name like '" + arg + "%'"
where arg is a string.

I managed to solve the problem, I still don't know why this was happening but at least I got the Cursor to actually select the rows.
After many trials I thought about ditching the syntax above and write this instead:
" WHERE list.state = 'sold' and list.name like ? "
and move the argument in
selectionArgs = new String[]{arg + "%"}
I am going to wait a while before accepting the answer, in case someone provides an explanation as to why even though both queries look exactly the same they get different results.

How to check if a table exists in Android?

I'm trying to query on a table dormpolicy
String operatorName = "46001";
String selection = "(plmn = '"+operatorName+"')";
URI CONTENT_URI_DORMPOLICY = Uri.parse("content://nwkinfo/nwkinfo/dormpolicy");
cursor = phone.getContext.getContentResolver().query(CONTENT_URI_DORMPOLICY, null, selection, null, null);
I get error log:
SQLiteQuery: exception: no such table: dormpolicy;
query: SELECT * FROM dormpolicy WHERE ((plmn = '46001'))
This issue happen not always in my phone.
It seems that sometimes,when I access the table before the table was created.
Is there any way that before I query the table, I check if the table exist?
And how?

My answer is twofold:
To strictly answer the question, I will redirect you to How does one check if a table exists in an Android SQLite database?
But rather than manually checking for tables' existence, I suggest you use the SQLiteOpenHelper class. This will help you manage your tables in a structured way. That includes handling database upgrades. Have a look at this for a quick start: http://developer.android.com/guide/topics/data/data-storage.html#db

android database through SQLIteDatabase

I am trying to learn the SQL Database stuff for SQLite using the android. I have seen a couple examples of the Queries....
I have a two part question about sqlite queries in android.
Part 1
Say I want to delete something. and I use the following Query.
db.delete(MY_DB_TABLE, "CustomerName = ?", new String[] { customerName });
what would happen if the Customer name had a bad character in it.
For example. If I use the following Query
db.execSQL("delete from " + MY_DB_TABLE +
" where customername = '" + customerName + "';");
and say for this example the name of my customer was "Arby's".
That query would blow up because the ' is a special character and the query would not be formatted correctly.
Part 2
does this format allow me to specify as many paramaters as I want.
Example:
db.delete(MYTABLE, "val1 = ? and val2 != ?", new String[] { "test", "test2" } );

Please refer to my post here:
Storing Lists to A Database, and Retrieving Them All Together : Android
and short answer to your question, yes.
Each '?' means that an argument will be expected, so for each '?' you WILL have an exact number of arguments to pass in unless you want an exception :) !