Four Parameters of contentresolver query ()

Public final cursor
Query (URI Uri,
String [] projection, string selection,
String [] selectionargs, string sortorder)

Since: API Level 1

Query the given Uri, returningCursorOver the result set.

For best performance, the caller shocould follow these guidelines:

• Provide an explicit projection, to prevent reading data from storage that aren't going to be used.
• Use question mark parameter markers such as 'phone =? 'Instead of explicit values in
  selectionParameter, so that queries that differ only by those values will be recognized as the same for caching purposes.

Parameters

Uri	The URI, using the content: // scheme, for the content to retrieve.
Projection	A list of which columns to return. Passing null will return all columns, which is inefficient.
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 Uri.
Selectionargs	You may include? S in selection, which will be replaced by the values from selectionargs, in the order that they appear in the selection. The values will be bound as strings.
Sortorder	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, or null

The above is written in API 2.2.
An SQL statement is as follows:
Select * From anytable where Var = 'const'
Anytable is Uri, * Is projection, and selection is "Var =? ", Selectionargs is written as follows: New String [] {'const '}
The last one is simple, that is, the sorting method.