CLOSE
CLOSE in SQL is a command used in the context of cursors. It effectively terminates a cursor that has been opened and populated with a fetch statement, thereby ceasing any further operations within that cursor. The associated resources are freed up, but the cursor is still available for re-open.
Example
DECLARE emp_cursor CURSOR FOR SELECT * FROM employees;BEGIN OPEN emp_cursor; CLOSE emp_cursor;END;
Output
This script won’t generate a visible output, because the cursors don’t produce visible outputs in Oracle database.
Explanation
In the Example
, a cursor emp_cursor
is declared, which fetches all records from the employees
table. The OPEN
statement opens the cursor, making it ready to fetch the data. The CLOSE
statement, which is the focus of this example, is used to close the cursor emp_cursor
after the usage. Since a closed cursor cannot be referenced, the CLOSE
statement is essential to free up the memory in the database environment.
Example
DECLARE @sales CURSOR;SET @sales = CURSOR FORSELECT * FROM SalesOPEN @sales--perform operationsCLOSE @sales
Output
Command(s) completed successfully.
Explanation
In the above SQL Server code snippet, a cursor named @sales
is being declared and set to select all records from the Sales table. The OPEN
statement initiates the cursor, and after executing required operations, the CLOSE
statement is used. This closes the cursor and releases the current result set. However, it does not deallocate resources. A cursor must be closed before it can be reopened. The output shows that the commands have been carried out successfully.