What is database cursor in SQL Server?

What is a database cursor in SQL?

In computer science, a database cursor is a mechanism that enables traversal over the records in a database. … 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.

What is a cursor in database?

A database cursor is an identifier associated with a group of rows. It is, in a sense, a pointer to the current row in a buffer. … Statements that return more than one row of data from the database server: A SELECT statement requires a select cursor. An EXECUTE FUNCTION statement requires a function cursor.

What is the use of cursor in SQL Server?

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.

What is cursor in SQL Server with example?

Cursor is a database object to retrieve data from a result set one row at a time, instead of the T-SQL commands that operate on all the rows in the result set at one time. We use a cursor when we need to update records in a database table in singleton fashion means row by row.

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What are the types of cursor?

There are 2 types of Cursors: Implicit Cursors, and Explicit Cursors. These are explained as following below. Implicit Cursors: Implicit Cursors are also known as Default Cursors of SQL SERVER.

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.

What is cursor example?

Oracle creates a memory area, known as the context area, for processing an SQL statement, which contains all the information needed for processing the statement; for example, the number of rows processed, etc. A cursor is a pointer to this context area. … A cursor holds the rows (one or more) returned by a SQL statement.

What is difference between trigger and cursor?

A cursor is activated and thus created in response to any SQL statement. A trigger is executed in response to a DDL statement, DML statement or any database operation.

Should I use cursor SQL?

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.

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.

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How do you write a trigger?

create trigger [trigger_name]: Creates or replaces an existing trigger with the trigger_name. [before | after]: This specifies when the trigger will be executed. {insert | update | delete}: This specifies the DML operation. on [table_name]: This specifies the name of the table associated with the trigger.

What are the types of cursor in SQL?

SQL Server supports three cursor implementations.

  • Transact-SQL cursors. Transact-SQL cursors are based on the DECLARE CURSOR syntax and used mainly in Transact-SQL scripts, stored procedures, and triggers. …
  • Application programming interface (API) server cursors. …
  • Client cursors. …
  • Forward-only. …
  • Static. …
  • Keyset. …
  • Dynamic.

How can I see the cursor in SQL?

Difference between View and Cursor in SQL :

  1. Declare the cursor in declaration section.
  2. Open the cursor in execution section.
  3. Fetch the cursor to retrieve data into PL/SQL variable.
  4. Close the cursor to release allocated memory.

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.