🗓️ 02102024 1035
📎 #mysql #wip
mysql_cursor_lifecycle
ABSTRACT
Step-by-step process that illustrates how cursors are typically used in SQL
Declare the Cursor
Defines the query whose result set the cursor will traverse
DECLARE cursor_name CURSOR FOR SELECT column1, column2 FROM table_name WHERE condition;
Open the Cursor
Allocates the memory for the cursor and populates it with the result set
OPEN cursor_name;
Fetch Data from the Cursor
Can fetch one row at a time or multiple rows (depending on the cursor type mysql_cursor)
FETCH NEXT FROM cursor_name INTO @variable1, @variable2;
| Command | Description |
|---|---|
FETCH | Retrieve individual rows from the cursor |
NEXT | Retrieves next row in result set |
INTO | Specifies variables where fetched values will be stored |
You can continue to fetch rows until no more rows are available.
Process Each Row
As each row is fetched, you can process it using procedural logic (e.g., updating values, inserting into another table, or performing calculations).
Close the Cursor
Release any locks or resources held by the cursor
CLOSE cursor_name;
Deallocate the Cursor
Optionally, after closing the cursor, you can deallocate it to remove the cursor from memory
DEALLOCATE cursor_name;