Oracle cursor

You must, of course, use the SQL language to access tables, and each time you do so, you use a cursor to get the job done. Oracle implicitly opens a cursor to process each SQL statement not associated with an explicit cursor. They provide information about the execution of data manipulation statements.

One can think of a cursor as a data structure that describes the returned from a SQL SELECT statement. A cursor is a pointer used to fetch rows from a result set. One of the variables in this structure is a pointer to the next record to be fetched from the query.

Oracle creates context area for processing an SQL statement which contains all information about the statement. The set of rows the cursor holds is referred as active set. Oracle defines an execution cycle to execute an SQL statement and associates a cursor with it.

The following illustration shows the execution cycle of an explicit cursor : Let’s examine each step in detail. Previous post we have explained detailed about different types of cursors. To execute a multi-row query, Oracle opens an unnamed work area that stores processing information.

Why do you use cursors in Oracle? When you do not need to close a cursor in Oracle? What is an open cursor in Oracle? How do you create a cursor in SQL? Multiple record and single column.

When a SQL statement is executed in Oracle , the temporary context area is created. This area contains all the relevant information relating to the statement and its execution. It is one of the core database programming concepts, which forms a basic unit of execution of SQL statement.

Cursors in Oracle DBMS. NET application that accesses Oracle Database 10g Release 2. Sample Application Requirements The sample application code that accompanies this column simulates a user selecting a subset of employees from an employees table. The below SQL statement converts the EMPLOYEES table into a cursor and nests it to each corresponding department that the employees fall on. Every single SQL parsed by the Oracle SQL engine becomes a cursor in the SQL Shared Pool. Every SQL you enter in TOAD or SQL-Developer.

All of them are cursors. You CANNOT bulk collect by not using a cursor. You need to assign value to V_Vbefore looping the cursor. NET Framework Data Provider for Oracle supports the Oracle REF CURSOR data type.

When using the data provider to work with Oracle REF CURSORs, you should consider the following behaviors. Some behaviors differ from those of the Microsoft OLE DB Provider for Oracle (MSDAORA). In SQL Server a cursor can be declared as LOCAL or GLOBAL.

There are basic types: Strong ref cursor and weak ref cursor For the strong ref cursor the returning columns with datatype and length need to be known at compile time. In Oracle cursors are always local i. For the weak ref cursor the structure does not need to be known at compile time. Home Articles Misc Here. This article demonstrates a few simple ways to display the contents of ref cursors. A SQL Server cursor is a mechanism for stepping through a result set one row at a time.

These are two totally different functions. The query returns only columns, but the second column is a cursor that lets us traverse a set of related information. Queries in CURSOR expression that find no rows do NOT raise NO_DATA_FOUND. REF CURSOR type has been available to allow recordsets to be returned from stored procedures and functions.

Oracle 9i introduced the predefined SYS_REFCURSOR type, meaning we no longer have to define our own REF CURSOR types.