Difference Between query and rawQuery in Android

In Android  Executing Queries using below methods

    Execute db.rawQuery method
    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:

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

Notes
The result of a query is returned in Cursor object.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:

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

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