Fetching and updating cursors updating c band satellite dish systems
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Visit Stack Exchange Database Administrators Stack Exchange is a question and answer site for database professionals who wish to improve their database skills and learn from others in the community. Sign up to join this community Static Cursor doesn't allow to modify the data because it's read only, and when executed with "Where current of", it returns error as expected. But i was surprised to find that static cursor allow to modify data with variable like this.
Locks on the base table are released, and only the worktable is used for fetching.
To declare cursor CI as an insensitive cursor, enter: The cursor reads the second row from the cursor result set, and returns Row 2, “2002020, Sam, Clarac.” This next command inserts one more qualified row (that is, a row that meets the query condition in mode, the cursor’s worktable materializes as the rows are fetched, rather than when you open the cursor.
The following diagram illustrates how to use a cursor in Postgre SQL: We will examine each step in more detail in the following sections.
Scan count 0, logical reads 8 Table '##Cursor Test'. Scan count 0, logical reads 2 Table '##Cursor Test'. Scan count 0, logical reads 2 Table '##Cursor Test'. Scan count 0, logical reads 2 Table '##Cursor Test'. Scan count 0, logical reads 2 Table '##Cursor Test'. Scan count 0, logical reads 2 being the better option, and a more complicated query for the Cursor might be an even bigger difference (assuming you are able to update based on the Clustered Key of the target table).
So in this context, when you make any updates to the underlying table of this static cursor, the changes will not be reflected back to the cursor (i.e. If I can make a quick logic summary (in my own understanding) When you create a static cursor, a tempory table in [Temp DB] is created and this temp table is read only, meaning you cannot use CURRENT OF to refer to this temp table and do any updates on it.
author au_id ------------------------- ----------- Johnson White 1 Marjorie Green 2 Cheryl Carson 2 Michael O’Leary 2 Dick Straight 2 Meander Smith 3 Abraham Bennet 4 Ann Dull 4 Burt Gringlesby 4 Chastity Locksley 4 Morningstar Greene 5 Reginald Blotchet Halls 6 Akiko Yokomoto 6 Innes del Castillo 7 Michel De France 7 Dirk Stringer 7 Stearns Mac Feather 7 Livia Karsen 7 Sylvia Panteley 8 Sheryl Hunter 8 Heather Mc Badden 8 Anne Ringer 8 Albert Ringer 9 (23 rows affected) When you declare and open an insensitive cursor, a worktable is created and fully populated with the cursor result set.
A PL/pg SQL cursor allows us to encapsulate a query and process each individual row at a time.
We use cursors when we want to divide a large result set into parts and process each part individually.