When a refcursor is defined with a return type, it is called as a strongly typed static refcursor. Its not allowed to use cursor variables in the for cursor loop for i in mycursor. Different behavior for ref cursor between oracle 10g and. This tutorial has been written in french and it would be too time consuming to translate it all in english. Using ref cursors 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 plsql data type whose value is the memory address of a query work area on the database.
Dec 20, 2016 i hope before knowing about ref cursors you would have a fair idea of what cursors in general are. In case you want to read the previous post oracle cursor basics all examples are tested in oracle 11g release 2 version. Using plsql stored procedures and ref cursors oracle. This behavior is consistent on every 10g or 11g instance ive tried 10. Strong plsql ref cursors burleson oracle consulting.
The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. It cannot be used in a ref cursor select statement. The example below uses a ref cursor to return a subset of the records in the emp table. Returning a ref cursor from a procedure plsql this example demonstrates how to define and open a ref cursor variable, and then pass it as a procedure parameter. Plsql ref cursor and oraclerefcursor oracle help center. This section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects.
Strong plsql ref cursors oracle plsql tips by boobal ganesan. On connection pools, cursor differentiation, and optimal. Using plsql stored procedures and ref cursors oracle docs. Anchor the cursor statement to a table or view in the database catalog. Access to oracle9i database or oracle database 10g. The steps in this section will help you create package specs that define ref cursors to define a ref cursor type.
In essence, a ref cursor allows you to store the result of a bulk collect from a table or any plsql cursor return set into a plsql table ram array and then reference the array with the ref cursor as a pointer. A ref cursor that specifies a specific return type. Understanding ref cursors so the cursor never contained any values, it just pointed to a result set that. When using the data provider to work with oracle ref cursors, you should consider the following behaviors. Ref cursors are not result sets but pointers to compiled sql statements. The central purpose of the oracle plsql language is to make it as easy and efficient as possible to query and change the contents of tables in a database. Here is the syntax for declaring an updatable cursor. For more information, see building a dynamic query with dynamic sql. Run operations using ref cursors in oracle database using.
Plsql ref cursor performance burleson oracle consulting. Free oracle magazine subscriptions and oracle white papers. The name ref cursor can be confusing because a ref cursor variable is not a cursor, but a variable that points to a cursor. Cursor variables are available to every plsql client. We will explain different types of cursors with simple examples. Run operations using ref cursors in oracle database using the wcf service model. A cursor lets you name the work area, access the information, and process the rows individually. However, it seems politically insensitive to use that language even though oracle published it as such. Cursor in, cursor out oracle magazine oracle blogs. Once the processing is complete we can use a ref cursor to pass the recordset out to an application. Dynamic sql with ref cursor burleson oracle consulting. Previous post we have explained detailed about different types of cursors. This example executes a plsql stored procedure that returns two ref cursor parameters, and fills a dataset with the rows that are returned.
Hi tom, i have a procedure which has a string as an in parameter and a ref cursor as an out parameter. But i was wrong in stating, that you need a stored function to return a ref cursor. Create a record structure to store rows of the reference cursor in an ordinary fetch, or a record structure and associative array collection data type to store a set of rows of the reference cursor. Ask tom fetch ref cursor to another ref cursor oracle. When you opt to use a weakly typed cursor, you can anchor it to a plsql structure that is a collection of a plsql record structure. This is known as an associative array, and commonly called a plsql table by folks who predate the oraclei documentation that oracle would prefer we forget. Here is an example script that performs dynamic sql and returns the data as a ref cursor. Defining cursor variables ref cursor return clause. It represents a cursor or a result set in oracle database. A userdefined cursor variable type that was defined as a ref cursor. To read more about ref cursor i have created a package to explain few different ref cursor examples. A cursor is a pointer to a private sql area that stores information. Run operations using ref cursors in oracle database using the. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql.
In 10g the cursor will contain the expected results but in 11g the cursor will be empty. Then, explicitly open the reference cursor into the variable. Sometimes, you want to lock a set of rows before you can update them in your program. In case you want to read the previous post oracle cursor basics. This script is available as part of the sample code download. I used the classic dept and emp tables to illustrate the examples. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. The ref cursor can be assigned to other ref cursor variables.
You need to fetch the ref cursor into transient memory or persistent storage normal or global temporary table. For more information, see querying data with plsql. The ref cursor is a datatype in the oracle plsql language. I cant close ref cusor becasue of losing my result set. Listing 1 creates a ref cursor and a regular cursor. We provide you with an oracle sample database named ot which is based on a global fictitious company that sells computer hardware including storage, motherboard, ram, video card, and cpu. You need to be able to copy and optionally transform any plsql ref cursor in a uniform way across all editions of oracle database from 10g release 1 and newer. However, sometimes, you may want to process a data set on a row by row basis. Oracle cursor examples oracle plsql technology blog.
The openforusing statement associates a cursor variable with a query, executes the query, identifies the result set, positions the cursor before the first row in the result set, then zeroes the rowsprocessed count kept by %rowcount. Hence you close a ref cursor after you fetch from it. The sample code illustrates how simple it is to begin using ref cursors in your. 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. Home database oracle database online documentation, 10g release 2 10. Oracle provides the for update clause of the select statement in an updatable cursor to perform this kind of locking mechanism. You have to fetch from the cursor variable explicitly one row at a time, using fetch into statement and regular loop statement for instance or use fetch bulk collect into to populate a collection. The steps in this section will help you create package specs that define ref cursors. A cursor variable can be associated with different queries at runtime. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor.
First, a ref cursor can be dynamically opened and defined at runtime, in contrast to a regular cursor, which is static and defined at compile time. The refcursor declared in this programs scope is never opened as when it is assigned to the same refcursors variable in the out parameter, the information of the cursor variable from the server program is copied into this variable, thus making it its alias. For more information, see building a dynamic query with dynamic sql because this statement can use bind variables to make the sql. The first block provides an example of a strongly typed cursor variable, while the following two examples are examples of weakly typed cursor variables. If the ref cursor datatype is obtained as an oraclerefcursor object, it can be used to.
The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. In essence, a ref cursor is a pointer or a handle to a result set on the database. The ref cursor is a data type in the oracle plsql language. To execute a multirow query, oracle opens an unnamed work area that stores processing information. The advantage that a ref cursor has over a plain cursor is that is can be passed as a variable to a procedure or a function. If you lose your result set that indicates you are not done with the ref cursor.
I just open the ref cursor for a query with a where clause equal to in parameter. Understanding ref cursors so the cursor never contained any values, it just pointed to a result set that you processed. All examples are tested in oracle 11g release 2 version. We can allocate different storage locations to the cursor when the program runs. Using ref cursors is one of the most powerful, flexible, and scalable ways to return query results from an oracle database to a client application. Creating a plsql stored procedure that uses ref cursors. This variable is then looped for processing the returned result set as shown in. I wrote a stored procedure using ref cursor,and be a data set of reporting service. Here is a collection of oracle forms 10g sample dialogs extracted from a complete oracle forms tutorial. A cursor is a pointer to a private sql area that stores information about the processing of a select or dml statements like insert, update, delete or merge. To use these examples, you may need to create the oracle tables, and you must create a plsql package and package body. Now we create a print procedure that receives a ref cursor and prints the row data create or.
Creating aplsql stored procedure that uses ref cursors. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. Cursor is a mechanism which facilitates you to assign a name to a select statement and manipulate the information within that sql statement. It isnt a limitation, it is a great benefit to scalability.
To create a ref cursor query, you first create a package spec that defines the ref cursor. Net 10g release 2, you are now able to easily pass a ref cursor as an input. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. A variable created based on such a data type is generally called a cursor variable. Net type for the ref cursor type this section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects obtaining an oraclerefcursor object. Net framework data provider for oracle supports the oracle ref cursor data type. I am trying to execute a userdefined oracle function that returns a refcursor using odp. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions.
As i said in one comment, a puresimple selectstatement does not work in plsql. First we create a temporary table to hold the data during the processing. Declare type empcurtyp is ref cursor return emp%rowtype. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. The following example demonstrate passing a ref cursor. Can you show an example of a ref cursor with dynamic sql.
983 511 1429 767 42 1236 708 461 263 771 244 1535 1318 1461 1510 579 941 376 766 1353 758 1533 1168 775 1189 514 721 146 1098 998 255 469 177 1340 33 1250 252 1271