Contents
When working with MySQL cursor What must?
When working with MySQL cursor, you must also declare a NOT FOUND handler to handle the situation when the cursor could not find any row. Because each time you call the FETCH statement, the cursor attempts to read the next row in the result set.
When would you use a database cursor?
The reason you may need to use a database cursor is that you need to perform actions on individual rows. It updates every row in the table esqlSalesPerson where the SalesPersonID is less than 10031. If, during the update operation, there is an error, then no rows are updated.
When should you close a cursor?
Use close() when you are done using a cursor. This method closes the cursor, resets all results, and ensures that the cursor object has no reference to its original connection object.
How do I run a cursor in MySQL?
- Declaration of a Cursor. To declare a cursor you must use the DECLARE statement.
- Open a Cursor. For opening a cursor we must use the open statement.
- Fetch the Cursor. When we have to retrieve the next row from the cursor and move the cursor to the next row then you need to fetch the cursor.
- Close the Cursor.
Is it mandatory to close a cursor?
In your code example CURSOR is declared as part of procedure (not as part of package), which means, cursor is closed automatically when procedure executioin is complete. However it is best coding practice to CLOSE cursor statement if you have OPEN cursor statement in code.
Why do we need to close cursor in SQL?
CLOSE leaves the data structures available for reopening, but fetches and positioned updates are not allowed until the cursor is reopened. CLOSE must be issued on an open cursor; CLOSE is not allowed on cursors that have only been declared or are already closed.
When do you declare a cursor in MySQL?
MySQL cursor is asensitive. You can use MySQL cursors in stored procedures, stored functions, and triggers. First, declare a cursor by using the DECLARE statement: The cursor declaration must be after any variable declaration. If you declare a cursor before the variable declarations, MySQL will issue an error.
Which is the cursor for stored procedures in MySQL?
Stored procedures are the set of SQL statements that are kept in RDMS as a group with a name assigned for the aim of reuse and sharing functions by many programs. Below are the Features of MySQL Cursor: Read-Only: You cannot modify any data in the primary table using the cursor.
Is the MySQL cursor read only or scrollable?
MySQL cursor is read-only, non-scrollable and asensitive. Read-only: you cannot update data in the underlying table through the cursor. Non-scrollable: you can only fetch rows in the order determined by the SELECT statement. You cannot fetch rows in the reversed order.
How is the cursor in MySQL asensitive to the data?
In an asensitive cursor, the actual data is pointed while in an insensitive cursor, a provisional copy of the data is used. Thus, MySQL cursor is asensitive. When any SQL statement is executed, then a temporary workspace is generated in the system memory, this space is Cursor. A cursor holds a set of rows which is known as Active set.