What is cursor in Teradata?
Teradata Preprocessor2 uses cursors to mark or tag the first row accessed by an SQL query. Preprocessor2 then increments the cursor as needed. Result set cursors to return the result of a SELECT statement executed in the stored procedure to the caller of the stored procedure or the client application.
What is cursor and types?
Cursor is a Temporary Memory or Temporary Work Station. It is Allocated by Database Server at the Time of Performing DML(Data Manipulation Language) operations on Table by User. Cursors are used to store Database Tables. There are 2 types of Cursors: Implicit Cursors, and Explicit Cursors.
What is cursor with diagram?
A cursor is a temporary work area created in the system memory when a SQL statement is executed. A cursor contains information on a select statement and the rows of data accessed by it….Cursors.
| Cursor Attributes | |
|---|---|
| Name | Description |
| %FOUND | Returns TRUE if record was fetched successfully, FALSE otherwise. |
What is implicit cursor in SQL server?
Implicit cursors are automatically created by Oracle whenever an SQL statement is executed, when there is no explicit cursor for the statement. For INSERT operations, the cursor holds the data that needs to be inserted. For UPDATE and DELETE operations, the cursor identifies the rows that would be affected.
What are the main feature of cursor?
Cursors are used by database programmers to process individual rows returned by database system queries. Cursors enable manipulation of whole result sets at once. In this scenario, a cursor enables the sequential processing of rows in a result set.
What is the use of cursor?
Use 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.
What is cursor in stored procedure?
In SQL procedures, a cursor make it possible to define a result set (a set of data rows) and perform complex logic on a row by row basis. Open the cursor to establish the result set. Fetch the data into local variables as needed from the cursor, one row at a time.
What are implicit cursor attributes?
An implicit cursor has attributes that return information about the most recently run SELECT or DML statement that is not associated with a named cursor. You can use cursor attributes only in procedural statements, not in SQL statements.
What are the main features of cursor?
Open: A Cursor is opened and populated by executing the SQL statement defined by the cursor. Fetch: When the cursor is opened, rows can be fetched from the cursor one by one or in a block to perform data manipulation. Close: After data manipulation, close the cursor explicitly.
What is the function of a cursor?
In computer user interfaces, a cursor is an indicator used to show the current position for user interaction on a computer monitor or other display device that will respond to input from a text input or pointing device. The mouse cursor is also called a pointer, owing to its resemblance in usage to a pointing stick.
What is the purpose of a cursor?
A cursor keeps track of the position in the result set, and allows you to perform multiple operations row by row against a result set, with or without returning to the original table. In other words, cursors conceptually return a result set based on tables within the databases.
What is cursor in procedure?
In SQL procedures, a cursor make 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 does the declared cursor do in Teradata?
Specifies whether the declared cursor can fetch the next row in the result set, or fetch the first row in the result set from any location in that set. SCROLL can either scroll forward to the next row in a result set or scroll directly to the first row in the result set.
Is there an updateable cursor in SQL assistant?
Updateable cursors can only be reported in ANSI transaction mode. You cannot create a Stored Procedure with an updateable cursor from your SQL assistant as SQL assistant runs in Teradata transaction mode. You will have to compile your stored procedure from BTEQ in ANSI mode.
When to use the cursor in the SELECT statement?
The SELECT statement that retrieves the rows the cursor reads or updates. Specifies that you can only use the cursor to read the rows in the result set. This is the default. Specifies that you can use the cursor to update or delete the rows in the result set. The identifier for the dynamic form of the DECLARE CURSOR statement.
When do you close the cursor in SQL?
There are two SQLSTATES which are essential when iterating over a cursor: You can use the SQLSTATE ‘02000’ to determine when you reached the data set’s end. As soon as you don’t need the result set anymore, the cursor should be closed to free up the spool space. Here is the syntax: