Structured Query Language

                   OPEN Cursor






Syntax:

OPEN cursor_name

where
 
cursor_name

  Specifies the name of an already-declared cursor. At the time the
  cursor is opened, results set membership and ordering are fixed. 
 
Note:
  
  Following is specific for  MS-SQL Server & SYBASE
  
  In the case of an INSENSITIVE cursor, this will generate the required
     temporary table.
  Membership and ordering are fixed when the cursor is opened; updates
     and deletes that have been committed against the base tables of the
     cursor by other users will be reflected in fetches made against all
     cursors defined without the INSENSITIVE option. This behavior is
     commonly called keyset-driven. Rows that have been deleted from a
     results set will appear with NULLs in all variable columns, spaces
     in all char columns, and default or zero values in all other
     non-null columns. To differentiate between a deleted row and a row
     that has been inserted with NULL data values, use the global
     variable @@FETCH_STATUS after each FETCH is made against the cursor.









Remarks:

  Once a cursor has been opened, use the global variable @@CURSOR_ROWS
  to receive the number of qualifying rows in the last opened cursor.
  Depending on the number of rows expected in the results set, SQL
  Server may choose to populate the keyset asynchronously on a separate
  thread. This allows fetches to proceed immediately, even if the keyset
  is not fully populated. @@CURSOR_ROWS returns:
    
-m  If the cursor is being populated asynchronously. The value
    returned (-m) refers to the number of rows currently in the keyset.
    
 n  If the cursor is fully populated. The value returned (n) refers to
    the number of rows.
    
 0  If no cursors have been opened or the last opened cursor has been
    closed or deallocated.
 
To set the threshold at which SQL Server will generate keysets
asynchronously, use the cursor threshold configuration option.
For details, see the sp_configure system stored procedure.
 

SQL Tutorial & Tips

Select
Insert
Update
Delete
Open Cursor
Fetch
Close Cursor
Union