Static Cursor, Dynamic Cursor, and Keyset-Driven Cursor in SQL Server

Before reading this article visit,Cursor in SQL Server.

 

Introduction

 

In this article, I describe Static Cursor, Keyset-Driven Cursor, and Dynamic Cursor.

 

First, we are creating a table.

 

Creation of table

create table emp(empId int, empName varchar(10))

Insertion of data

insert into emp
select 1,'d'union all
select 2,'e'union all
select 3,'e'union all
select 4,'p'union all
select 5,'a'union all
select 6,'k'

Output

select * from emp

 

 

Static Cursor

 

A Static Cursor shows the result set as it was when the cursor was opened. If we make change to the table after the opening of Static Cursor then these changes are not reflected in the cursor. For example, if after opening the cursor we delete a row, and fetch that record by the cursor, then the cursor shows that record.

 

Syntax

 

Declare cursorName cursor

static for

statement

 

Here cursorName is the name of your cursor, static is a keyword, and statement is the SQL statement that you are used in the cursor. An example is given below.

 

Creation of Static Cursor 

declare static_cursor cursor
static for
select * from emp

Opening of Static Cursor

open static_cursor

Fetching data from Static Cursor

Fetching first data from Static Cursor

fetch first from static_cursor

Output

 

 

 

Fetching next data from Static Cursor

fetch next from static_cursor

Output

 

 

 

Fetching last data from Static Cursor

fetch last from static_cursor

Output

 

 

 

Fetching second data from Static Cursor

fetch absolute 2 from static_cursor

Output

 

 

 

Fetching next 2nd data from Static Cursor

fetch relative 2 from static_cursor

Output

 

 

 

Closing of Static Cursor

close static_cursor

Deallocating Static Cursor

deallocate static_cursor

Dynamic Cursor

 

Dynamic Cursor is the opposite of the Static Cursor. When we make changes in the table after opening the Dynamic Cursor and scroll through a Dynamic Cursor all changes made to the table reflects the Dynamic Cursor. For example, If we delete the record from the table after the opening of the Dynamic Cursor, we can't access that record.

 

Syntax

 

Declare cursorName cursor

Dynamic for

statement

 

Here cursorName is the name of your cursor, Dynamic is a keyword, and statement is the SQL statement that you are used in cursor. An example is given below.

 

Creation of Dynamic Cursor

declare dynamic_cursor cursor
dynamic for
select * from emp

Opening of Dynamic Cursor

open dynamic_cursor

Fetching first data from Dynamic Cursor

fetch First from dynamic_cursor

Output

 

 

 

Fetching next data from Dynamic Cursor

fetch next from dynamic_cursor

Output

 

 

 

We can fetch last, relative and absolute data same as Static Cursor.

 

Closing of Dynamic Cursor

close dynamic_cursor

Deallocating  Dynamic Cursor

deallocate dynamic_cursor

Keyset-Driven Cursor

 

When we open keyset-driven cursor then it creates a list of unique values in the tempdb database. These values are called keyset. Every keyset uniquely identifies a single row in the result set.

 

A Keyset is created after the opening of the cursor so the number of rows is fixed until we close the cursor.

 

Creation of Keyset-driven cursor

declare key_cursor cursor
keyset for
select * from emp

Opening of Keyset-driven cursor

open key_cursor

Fetching data from Keyset-Driven cursor 

 

Fetching first data from Keyset-driven cursor

fetch First from key_cursor

Output

 

 

 

Fetching next data from Keyset-driven cursor

fetch next from key_cursor

Output

 

 

 

Closing of Keyset Drivin cursor

close key_cursor

Deallocation of memory

deallocate key_cursor

Summary

 

In this article, I described Static Cursor, Dynamic Cursor, and Keyset-Driven Cursor. I hope this article has helped you in understanding this topic. Please share it. If you know more about this, your feedback and constructive contributions are welcome.