Asked by: Ruyi
Asked in category: technology and computing, databases
Last Updated: 9th May 2024
What is cursor in SQL interview?
A Cursor, a database object, is used to manipulate rows row by row. FETCH statements can be used with Transact- SQL Cursors in order to retrieve rows from a results set. API server cursors are compatible with the API cursor functions.
Similar, what does SQL cursor refer to?
Temporary work area
What is cursor in SQL? Oracle creates a memory space, called the context area, to process an SQL statement. This area contains all information necessary for processing the statement. A cursor points to this context area. A cursor stores the rows returned by a SQL query (one or more).
You might also ask: What is a cursor? In SQL? Why do you need it in SQL?
Use of Cursor A cursor's primary function is to retrieve data from a result list one row at time. SQL commands, on the other hand, operate on all rows in the result set at once. When a user wants to modify records one-by-one or row by row in a database table, cursors can be used.
SQL cursors are bad?
SQL Cursors can be used as long as they use the right options. INSENSITIVE will create a temporary copy (saving you from having this done manually for your pseudo-cursor). READ_ONLY will ensure that no locks are placed on the underlying result sets.
17 Related Question Answers Found
What is Iscursor?
1) A cursor is the position indicator on a computer display screen where a user can enter text. In an operating system with a graphical user interface (GUI), the cursor is also a visible and moving pointer that the user controls with a mouse, touch pad, or similar input device.
How do I create a cursor?
In the above syntax, the declaration part contains the declaration of the cursor and the cursor variable in which the fetched data will be assigned. The cursor is created for the 'SELECT' statement that is given in the cursor declaration. In execution part, the declared cursor is opened, fetched and closed.
How do cursors 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 are views in SQL?
In SQL, a view is a virtual table based on the result-set of an SQL statement. The fields in a view are fields from one or more real tables in the database. You can add SQL functions, WHERE, and JOIN statements to a view and present the data as if the data were coming from one single table.
What is the use of mouse pointer?
A mouse cursor, also known as a mouse arrow, or mouse pointer, is a graphical image that is used to activate or control certain elements in a graphical user interface. More plainly, it indicates where your mouse should perform its next action, such as opening a program, or dragging a file to another location.
What is cursor for kids?
A cursor is a shape on a computer screen that shows where actions made with the keyboard or mouse will make a change. The Mouse cursor: The pointer on the screen which the person using the computer can move using the computer mouse. This cursor allows the person to select or "click" items with the mouse.
What are SQL triggers?
A trigger is a special type of stored procedure that automatically runs when an event occurs in the database server. DML triggers run when a user tries to modify data through a data manipulation language (DML) event. DML events are INSERT, UPDATE, or DELETE statements on a table or view.
Which is faster cursor or while loop?
Not really. In terms of what it is doing, a while loop and a cursor both do the same thing, they operate on one row at a time. A lot of people when trying to remove cursor-based code, simply replace it with a while loop, in the hope that it will run faster, because it's not a *nasty* cursor.
What is a cursor in MySQL?
Introduction to MySQL cursor
To handle a result set inside a stored procedure, you use a cursor. A cursor allows you to iterate a set of rows returned by a query and process each row individually. MySQL cursor is read-only, non-scrollable and asensitive. You cannot fetch rows in the reversed order.Why use triggers in SQL?
What is a Database Trigger? Triggers help the database designer ensure certain actions, such as maintaining an audit file, are completed regardless of which program or user makes changes to the data. The programs are called triggers since an event, such as adding a record to a table, fires their execution.
What is ref cursor in Oracle?
Introduction to REF CURSORs
Using REF CURSOR s is one of the most powerful, flexible, and scalable ways to return query results from an Oracle Database to a client application. A REF CURSOR is a PL/SQL data type whose value is the memory address of a query work area on the database.What happens when rows are found using a fetch statement?
What happens when rows are found using a FETCH statement 1. It causes the cursor to close 2. It loads the current row values into variables 4. It creates the variables to hold the current row values.
How do you eliminate duplicate rows from a query result?
The go to solution for removing duplicate rows from your result sets is to include the distinct keyword in your select statement. It tells the query engine to remove duplicates to produce a result set in which every row is unique. The group by clause can also be used to remove duplicates.
What is implicit cursor?
A SQL (implicit) cursor is opened by the database to process each SQL statement that is not associated with an explicit cursor. Every SQL (implicit) cursor has six attributes, each of which returns useful information about the execution of a data manipulation statement.
What is a cursor on iPhone?
With iPhone 6S, Apple introduced a feature which let the users long press anywhere on the keyboard to turn the phone into a trackpad that you could use as a cursor to select or highlight text - something you could do only on a laptop previously.
What is the difference between cursor and while loop in SQL Server?
Cursors in sql server allow you to fetch a set of data, loop through each record, and modify the values as necessary; then, you can easily assign these values to variables and perform processing on these values. While loop also same as cursor to fetch set of data and process each row in sql server.
What is difference between cursor and trigger?
Generally, a cursor is used to iterate through a result set that was returned by a SELECT statement. Cursors can be used in stored procedures, stored functions, and triggers. A trigger is a stored program executed automatically to respond to a specific event like an insert, update, or delete.
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