Develop Reference

How To Use SQLite COUNT in Android to return number of rows

I want to write a query that add up all the rows that have the string value of "left" in column named DIRECTION. Next I want to return this sum.
In my code snip-it below assume data and data base are established.
Here is the prototype:
public int getSumLeft() {
String selectQuery = "SELECT COUNT( "+TableData.TableInfo.DIRECTION+" ) WHERE "+TableData.TableInfo.DIRECTION+" = left";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
int sum = cursor.getInt(0);
cursor.close();
return sum;
}
I've tried several queries and this one seems to be the closes to what I need. I think the problem is with statement 'int sum = cursor.getInt(0);'
I think the zero parameter is overriding the results. When I remove the zero the code breaks. getInt is an SQLite function that is used to access data in the database. I did not create that function. But I must use it or and another function like it.
Also, do I need to put a while loop around the query to move the cursor for a COUNT query? Doesn't the Database count for you, therefor no need for iteration?
Is there another way of counting the rows where the string value is 'left' and the sum can be returned?
Full code here:
Database:
https://github.com/Leoa/Accelerometer/tree/AccelerometerDEV/app/src/main/java/thedatabase
Implementation (see the button in onCreate function ):
https://github.com/Leoa/Accelerometer/blob/AccelerometerDEV/app/src/main/java/com/leobee/accelerometer/MainActivity.java
Thanks for looking into this.

I think the zero parameter is overriding the results
I have no idea what you think that this means.
When I remove the zero the code breaks
That is because getInt() needs to know the column of the Cursor to retrieve.
You are also crashing at runtime, as your SQL is invalid. Your SQL statement amounts to:
SELECT COUNT(foo) WHERE foo = left
(where foo is whatever TableData.TableInfo.DIRECTION in Java refers to)
Not only does your SQL statement lack a table to query against, but if left is supposed to be the value of a string column, you need to quote it. You will wind up with something like:
SELECT COUNT(foo) FROM tablename WHERE foo = 'left'
do I need to put a while loop around the query to move the cursor for a COUNT query?
No.
Is there another way of counting the rows where the string value is 'left' and the sum can be returned?
Not really, other than the fix that I outline above.

I think the problem is you need to add quotes on the 'left'
String selectQuery = "SELECT COUNT( "+TableData.TableInfo.DIRECTION+" ) WHERE "+TableData.TableInfo.DIRECTION+" = 'left'"

SELECT entry in SQLite, without a WHERE condition?

I followed advice in this question, but for my purposes I don't want a WHERE.
I don't know the value, so I cannot say rawQuery("... WHERE x = ?", y), I don't care what y is, it's just a cell I want, and it is known that there is a single row.
If it is not possible to lose the condition (perhaps because of causing an indeterminate number of results?) - then how can I say "from column z and row 0"?
I'm lacking either terminology, or outright understanding, because my searches are turning up nothing.
Edit: Eclipse doesn't complain at:
result = db.rawQuery("SELECT col FROM tbl", my_unused_string_array);
I'm not at a testing stage yet, and I can't enter this into the SQL db reader I was using to test SELECT col FROM tbl and ~ with WHERE.. will it work?

As per your edit, you don't need to specify WHERE clause, if you want to get all the records from a table:
result = db.rawQuery("SELECT col FROM tbl", new String[0]);

The SQL query "SELECT * FROM table" will return the entire table. "SELECT colX, colY FROM table" will return columns colX and colY for all the rows in the table. If your table contains just one row, "SELECT col FROM table" will return the value of col for that one row.
To use the SQLiteDatabase API to make that query, you would say:
result = db.rawQuery("SELECT col FROM tbl", null);
... because you are not supplying any query parameters.
Assuming that there is just one row seems dangerous to me. I would not use the "LIMIT" clause, because, while that will always get one row, it will hide the fact that there is more than one row, if that happens. Instead, I suggest that you assert that the cursor contains one row, like this:
if (1 != result.getCount()) {
throw Exception("something's busted");
}

Instead of Raw query use
Cursor cur = db.query(Table_name, null, null, null, null,
null, null);
and get the desired attributes from cursor.
where the query method has parameters in following manner:
public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
Parameters:
table The table name to compile the query against.
columns A list of which columns to return. Passing null will return all columns, which is discouraged to prevent reading data from storage that isn't going to be used.
selection A filter declaring which rows to return, formatted as an SQL WHERE clause (excluding the WHERE itself). Passing null will return all rows for the given table.
selectionArgs You may include ?s in selection, which will be replaced by the values from selectionArgs, in order that they appear in the selection. The values will be bound as Strings.
groupBy A filter declaring how to group rows, formatted as an SQL GROUP BY clause (excluding the GROUP BY itself). Passing null will cause the rows to not be grouped.
having A filter declare which row groups to include in the cursor, if row grouping is being used, formatted as an SQL HAVING clause (excluding the HAVING itself).
Passing null will cause all row groups to be included, and is required when row grouping is not being used.
orderBy How to order the rows, formatted as an SQL ORDER BY clause (excluding the ORDER BY itself). Passing null will use the default sort order, which may be unordered.
Returns
A Cursor object, which is positioned before the first entry.

Selecting int values using a cursor query

I am new to Android, and having some basic problems. One of them is the use of queries.
I store a boolean value as either 1 or 0 in the table (INTEGER field). However, when I select either on 1 or 0 using the query below I get no results. What am I doing wrong?
Cursor cursor = _db.query(_objectName, _fields.keySet().toArray(new String[0]), "parentId=? AND published=?", new String[] {String.valueOf(menuItem), String.valueOf(1)}, null, null, "level");

There is nothing wrong with your query. The problem must be elsewhere. Check your code and table structure. Maybe you are not sending the right values for parentId and published columns or the data in the table is not in the format you expected.

Use raw query
"Select * from "+TABLE_NAME+" where published = '"+String.valueOf(1)+"'";
You can put your integer value insted of 1

How to order sqlite table according to accending integer?

I am having some problems with ORDER BY in android sqlite.
I am using this query to reorder my listview :
Select * From tbl_name ORDER BY WithOrder asc
Where WithOrder is an Integer type column. The expected behavior I was hoping for was that sqlite will reorder the rows as ....8,9,10,11,12.... but it is reordering the list according to the first digit instead as ....10,11,8,9....
Please help me with reordering the table with ascending values of integer...I can not opt for any other column or datatype to reorder as I depend heavily on WithOrder for general calculations when the user reorders the list.
Thanks!
Parvaz Bhaskar

While numbers are sorted according to their numerical value, strings are sorted lexicographically, beginning with the first character.
In particular, the character 1 is less than the character 8, so any string beginning with 1 (such as 11) is sorted before any string beginning with 8.
Recreate your table so that the WithOrder column has type INTEGER.

Cursor c = SQLiteDatabase_OBJ.query("Table_name", null, null, null, null, null, "WithOrder ASC");
Try this

Try this ORDER BY CAST(WithOrder AS INTEGER) ASC

rawQuery wild card `"_"` not working

I have been trying to use the character wild card "_" in sqlite where conditions and am close to "jumping off a high place" I have tried both rawQuery and query with a variety of hard and soft coded parameters. It seems to ignores the character wild card "_"and returns all rows or none at all.
The data held is in several columns representing a features of an oblect for example a column may represent the colours of an object
("red,orange,yellow,green,blue,indego,violet,black")
and a row's colour could be "01001000" meaning that it is orange and blue but not red, yellow etc. other columns contain single characters ie size contains s,m or l (mapping small, medium, large ) the database holds several columns of each type, the idea to have as compact a database as possible.
My first intention was to code by passing the 'where' of my select as a string to the rawQuery(myselect,null) where the myselect was compiled in the code in response to several features selected by the user.
ie
the mywhere string is compiled to return :-
colour1 like "_1__10__" and colour2 like "___1_01__" and size ="l"
and passed to the rawQuery
db.rawQuery("SELECT _id , name FROM widgets WHERE " + mywhere , null);
The statement below works fine using Firefox's SQLite Manager
SELECT _id , name FROM widgets WHERE colour1 like "_1__10_" and colour2 like "__1_01___" and size ="m"
In order to investigate I have cut the query down to one column in the where clause
myselect ="SELECT _id ,name,FROM widgets where colour1 like \"1_______\"";
cursor = db.rawQuery(myselect,null);
returns no rows
myselect ="SELECT _id ,name,FROM widgets where colour1 like \"%1_______%\"";
cursor = db.rawQuery(myselect,null);
returns rows but not all have a 1 at the first char ( I expected this )
myselect ="SELECT _id ,name, FROM widgets where colour1 like ?";
String[] whereArguments = { "1_______" };
cursor = db.rawQuery(myselect,whereArguments);
returns no rows
myselect ="SELECT _id ,name, FROM widgets where colour1 like ?";
String[] whereArguments = { "%1_______%" };
cursor = db.rawQuery(myselect,whereArguments);
returns rows but not all have a 1 at the first char
But I dont get any rows from
myselect ="SELECT _id ,name, FROM widgets where colour1 like ?";
String[] whereArguments = { "10000000" };
cursor = db.rawQuery(myselect,whereArguments);
and there are rows containing "10000000"
Does any one have any solutions? I have tried searching but it seems that rawQuery and query have questionable functionality in Android.

Not sure if this is your main source of problems, but the string delimiter in SQLite is the single quote character (') not the double quote one ("). See this, for example.