Android - Fetching only rows with a value in a column in java

Question

First of all, please bear with me, I have minimal experience with SQLite. I am writing an app in Java for the Android platform and I've run into an issue while attempted to query a SQLite database.

I have implemented a database and I am unsure of how to write a method which returns a cursor of only specific rows with a certain value in a certain column. Say there is a column titled "date", I would like to write a method which returns all the columns that do not have the value string "null" in the "date" column.

I know how to write a fetchAll() method and how to write a fetch() for specific rows given an ID, but I not multiple specific rows.

If anyone can help me it would be greatly appreciated.

Rasel · Accepted Answer · 2011-07-23 05:36:12Z

4

These will return all the row where Date!=null

public Cursor fetch() 
        {
            return db.query(DATABASE_TABLE,
                    null, 
                    DATE + "!=''",
                    null,
                    null, 
                    null, 
                    null);                        


        }

If you don't need all columns then use

public Cursor fetch() 
            {
                return db.query(DATABASE_TABLE,new String[] {
                    DATE,
                    TIME
                    },                        
                        DATE + "!=''",
                        null,
                        null, 
                        null, 
                        null);                           


            }

edited Jul 23, 2011 at 5:36

answered Jul 23, 2011 at 5:22

Rasel

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Comments

Ash · Accepted Answer · 2011-07-23 09:27:26Z

For fetching multiple row using curosor, Have a go with this, You could customize it for your need:

public List<String> getNotNullValues(String value) {
        String[] resultCols = new String[] { "Give your result column name here" }; //u could specify multiple column name here
        List<String> list = new ArrayList<String>();
        int count = 0;
        Cursor cr = getWord("DATE", "Your Table Name", "Value of the column",
                resultCols,"!="); //Cr is the cursor for resulted query
        if (null == cr) {
            return null;
        }
        do {
            list.add(cr.getString(0)); //Fill the list or whatever here while traversing with the cursor

        } while (cr.moveToNext());
        cr.close();
        return list;
    }

}



public Cursor getWord(String columnName, String tblName, String rowId,
            String[] columns, String condition) {
        String selection = columnName + condition ;  //condtion for selecting a value : "= ?"
        String[] selectionArgs = new String[] { rowId };

        return query(selection, tblName, selectionArgs, columns);
    }

here are the steps:

Form the query with condition, column name and required column name
Get the cursor to the resulting query
Move the cursor to the next record till cr.moveToNext() returns false

For further reference:

Complete Step by Step SQLite Example: http://mobile.tutsplus.com/tutorials/android/android-sqlite/

Youtube Video Tutorial

http://www.youtube.com/watch?v=kMaBTolOuGo

Multiple Table Creation http://androidforbeginners.blogspot.com/2010/01/creating-multiple-sqlite-database.html

PS: All the links are tested and working well!!

Happy Coding!!

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