A SQL Server cursor is a set of T-SQL logic to loop over a predetermined number of rows one at a time. The purpose for the cursor may be to update one row at a time or perform an administrative process such as SQL Server database backups in a sequential manner.
Is it good to use cursor in SQL?
SQL Cursors are fine as long as you use the correct options: INSENSITIVE will make a temporary copy of your result set (saving you from having to do this yourself for your pseudo-cursor). READ_ONLY will make sure no locks are held on the underlying result set.
How does cursor work in SQL?
In SQL procedures, a cursor makes it possible to define a result set (a set of data rows) and perform complex logic on a row by row basis. … A cursor can be viewed as a pointer to one row in a set of rows. The cursor can only reference one row at a time, but can move to other rows of the result set as needed.
What is the advantage of cursor?
Cursor basically works as for/While loop. Advantages of using Cursor: Using Cursor we can perform row by row processing so we can perform row wise validation or operations on each row. Cursors can provide the first few rows before the whole result set is assembled.
What can I use instead of cursor in SQL Server?
We can also use temporary tables instead of SQL cursors to iterate the result set one row at a time. Temporary tables have been in use for a long time and provide an excellent way to replace cursors for large data sets.
What are disadvantages of cursor?
What are the disadvantages of cursors?
- Uses more resources because Each time you fetch a row from the cursor, it results in a network roundtrip.
- There are restrictions on the SELECT statements that can be used.
- Because of the round trips, performance and speed is slow.
Why SQL cursor is bad?
Cursors could be used in some applications for serialized operations as shown in example above, but generally they should be avoided because they bring a negative impact on performance, especially when operating on a large sets of data.
What are the main features of cursor?
The major function of a cursor is to retrieve data, one row at a time, from a result set, unlike the SQL commands which operate on all the rows in the result set at one time. Cursors are used when the user needs to update records in a singleton fashion or in a row by row manner, in a database table.
What is the cursor life cycle?
SQL Cursor Life Cycle
A cursor is declared by defining the SQL statement. A cursor is opened for storing data retrieved from the result set. When a cursor is opened, rows can be fetched from the cursor one by one or in a block to do data manipulation. The cursor should be closed explicitly after data manipulation.
Which is faster cursor or while loop?
While SQL While loop is quicker than a cursor, reason found that cursor is defined by DECLARE CURSOR. Every emphasis of the loop will be executed inside system memory and consuming required server assets.
What are the different types of cursor?
Types of cursors
- STATIC CURSOR. A static cursor populates the result set during cursor creation and the query result is cached for the lifetime of the cursor. …
- FAST_FORWARD. This is the default type of cursor. …
- DYNAMIC. …
What are the benefits of cursor FOR loop?
PL/SQL cursor FOR loop has one great advantage of loop continued until row not found. In sometime you require to use explicit cursor with FOR loop instead of use OPEN, FETCH, and CLOSE statement. FOR loop iterate repeatedly and fetches rows of values from database until row not found.
Why use triggers in SQL?
Because a trigger resides in the database and anyone who has the required privilege can use it, a trigger lets you write a set of SQL statements that multiple applications can use. It lets you avoid redundant code when multiple programs need to perform the same database operation.