The cursor name is only valid within this scope. The cursor can be referenced by local cursor variables in the batch, stored procedure, or trigger, or a stored procedure OUTPUT parameter.
An OUTPUT parameter is used to pass the local cursor back to the calling batch, stored procedure, or trigger, which can assign the parameter to a cursor variable to reference the cursor after the stored procedure terminates. The cursor is implicitly deallocated when the batch, stored procedure, or trigger terminates, unless the cursor was passed back in an OUTPUT parameter. If it is passed back in an OUTPUT parameter, the cursor is deallocated when the last variable referencing it is deallocated or goes out of scope.
The cursor name can be referenced in any stored procedure or batch executed by the connection. The cursor is only implicitly deallocated at disconnect. All insert, update, and delete statements made by the current user or committed by other users that affect rows in the result set are visible as the rows are fetched. Because the cursor cannot be scrolled backward, however, changes made to rows in the database after the row was fetched are not visible through the cursor.
Forward-only cursors are dynamic by default, meaning that all changes are detected as the current row is processed. This provides faster cursor opening and enables the result set to display updates made to the underlying tables.
While forward-only cursors do not support backward scrolling, applications can return to the beginning of the result set by closing and reopening the cursor. STATIC Specifies that the cursor always displays the result set as it was when the cursor was first opened, and makes a temporary copy of the data to be used by the cursor.
All requests to the cursor are answered from this temporary table in tempdb. Therefore inserts, updates, and deletes made to base tables are not reflected in the data returned by fetches made to this cursor, and this cursor does not detect changes made to the membership, order, or values of the result set after the cursor is opened. Static cursors may detect their own updates, deletes, and inserts, although they are not required to do so.
For example, suppose a static cursor fetches a row, and another application then updates that row. If the application refetches the row from the static cursor, the values it sees are unchanged, despite the changes made by the other application. All types of scrolling are supported. The set of keys that uniquely identify the rows is built into a table in tempdb known as the keyset.
This cursor provides functionality between a static and a dynamic cursor in its ability to detect changes. Like a static cursor, it does not always detect changes to the membership and order of the result set. Like a dynamic cursor, it does detect changes to the values of rows in the result set.
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The Overflow Blog. Podcast Making Agile work for data science. Stack Gives Back Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Related Hot Network Questions. Question feed. The use of the cursors. The lifecycle of the cursor. Example of cursor Requirement of Example Create a Temporary table for students. Insert some dummy records into the created table for demonstrations. What is a cursor in SQL Server?
A Cursor is a SQL Server database object that is used to manipulate data in a result set on a row-by-row basis. It acts as a loop just like the looping mechanism found in any other programming language like C , VB.
We can use cursors when we want to do data manipulation operations like update, delete and etc on a SQL Server database table in a singleton fashion in other words row by row. Use of the cursors You know that in relational databases, operations are made on a set of rows called as a result sets. Let's take an example. Sometimes the application logic needs to work in singleton fashion in shorts row by row basis with one row at a time rather than the entire result set at once. This can be done using cursors in SQL Server.
Lifecycle of the cursor Here we will split the life cycle of the cursor into the following 5 different sections. Declare Cursor Before using a cursor, you first must declare the cursor. So, in this section, we will declare variables and restore an arrangement of values. Open This is the second section of the life cycle and Once a cursor has been declared, you can open it and fetch from it Fetch This is the third section of the life cycle and this is used to recover the information push by push from a cursor.
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