Difference between rawQuery() and query() in android Sqlite?

Executing Queries

To execute queries, there are two methods:

1. Execute db.rawQuery method
2. Execute db.query method
   

To execute a raw query to retrieve all departments:

Cursor getAllDepts()
  {
   SQLiteDatabase db=this.getReadableDatabase();
   Cursor cur=db.rawQuery("SELECT "+colDeptID+" as _id, 
        "+colDeptName+" from "+deptTable,new String [] {});
   
   return cur;
  }

The rawQuery method has two parameters:

1. String query: The select statement
2. String[] selection args: The arguments if a WHERE clause is included in the select statement
   

Notes

1. The result of a query is returned in Cursor object.
2. In a select statement if the primary key column (the id column) of the table has a name other than _id, then you have to use an alias in the form SELECT [Column Name] as _id cause the Cursor object always expects that the primary key column has the name _id or it will throw an exception .
   

Another way to perform a query is to use a db.query method. A query to select all employees in a certain department from a view would be like this:

public Cursor getEmpByDept(String Dept) {
   SQLiteDatabase db=this.getReadableDatabase();
   String [] columns=new String[]{"_id",colName,colAge,colDeptName};
   Cursor c=db.query(viewEmps, columns, colDeptName+"=?", 
        new String[]{Dept}, null, null, null);
   return c;
  }

The db.query has the following parameters:

1. String Table Name: The name of the table to run the query against
2. String [ ] columns: The projection of the query, i.e., the columns to retrieve
3. String WHERE clause: where clause, if none pass null
4. String [ ] selection args: The parameters of the WHERE clause
5. String Group by: A string specifying group by clause
6. String Having: A string specifying HAVING clause
7. String Order By by: A string Order By by clause