A Cursor is a database object that represents a result set and is used to manipulate data row by row. When a cursor is opened, it is positioned on a row and that row is available for processing.
For example, you can use a single UPDATE statement to update many rows of data. There are times when you want to loop through a series of rows a perform processing for each row. In this case you can use a cursor.
Syntax for Declaring Cursor
-- Syntax
DECLARE <CURSOR_NAME> CURSOR FOR SELECT <COLUMN_NAME> FROM <TABLE_NAME> WHERE <CONDITION>
Example for Declaring Cursor
-- Example
DECLARE INFO_CURSOR CURSOR FOR SELECT * FROM INFO WHERE ID >5
After declaring the cursor we can access the data. Before accessing the data of the cursor it must be opened by using open statement. Directly following a successful opening, the cursor is positioned before the first row in the result set.
Example for Opening Cursor
--Syntax
OPEN <CURSOR_NAME>
--Example
OPEN INFO_CURSOR
After opening cursor on a specific row in the result set with the fetch statement. A fetch operation transfers the data of the row into the application. Simply we can say by using fetch statement we read one by one row at a time in forward only by default.
Example for Fetching Cursor
--Syntax
FETCH <CURSOR_NAME>
--Example
FETCH INFO_CURSOR
Example for Closing Cursor
--Syntax
CLOSE <CURSOR_NAME>
--Exaple
CLOSE INFO_CURSOR
Example which demonstrate the use of Scrollable Cursor
This feature not available in SQL Server 2005. This is come from SQL Server 2008 and 2012
declare cur_std scroll cursor for select * from student --Declare a cursor named cur_std
open cur_std -- Open the cursor
fetch next from cur_std -- Fetch next records in the cursor and display it
fetch absolute 3 from cur_std --Fetch 3 records in the cursor
fetch prior from cur_std --Fetch previous record in the cursor