A weakly typed ref cursor has a return type that is dependant on the sql statement it executes, i. 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. All these oracle features and data access optimizations are generally not available in other thirdparty. The data represented by the ref cursor is accessed in a forwardonly, serial manner.
I assume this to mean that open fetches the result set of the query into some memory space in the server probably an area not part of the plsql memory space, after which every. This behavior is consistent on every 10g or 11g instance ive tried 10. Different from implicit and explicit cursors, a cursor variable is not tied to any specific query. Net framework data provider for oracle supports the oracle ref cursor data type. The third approach involves using oracle s cursor expressions in a single database call. The problem here is because oracle 10 g r2 doesnt support clobs as ref cursor, our procedure is failing when variable holding csv values grows to large extent. The oracle ref cursor is a pointer data types that allows you to quickly reference any cursor result usually an internal plsql table array with data values kept in superfast ram. Ive created an html form where the user can enter any combination of three values to retrieve results from the wine table. Much of these comes from the fact that packages are stored into the shared pool of the oracle database or otherwise known as pinned to memory. Different behavior for ref cursor between oracle 10g and 11g. Retrieving data from multiple ref cursors using an oracledatareader. What is the difference between a normal cursor and a ref. 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. A cursor variable has datatype ref cursor, and you might see them referred to informally as ref cursors.
When a refcursor is defined with a return type, it is called as a strongly typed static refcursor. Change the group of the dbora file to the osdba group typically dba, and set the permissions to 750. Im passing a ref cursor back from a function, how do i use the data in that ref cursor in my select statementquery and, equally as often, the problem comes from a lack of understanding what a ref cursor actually is. Procedure that outputs a dynamic plsql cursor question. You create and return a ref cursor inside a plsql code block. A cursor is a pointer to a private sql area that stores information.
The ref cursor is a datatype in the oracle plsql language. Listing 1 creates a ref cursor and a regular cursor. 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. As such it went into a loop, fetching each row of data from the database, using the ref cursor as its reference pointer to the relevant query, and displaying each row of data until it had no more rows to fetch. When using the data provider to work with oracle ref cursors, you should consider the following behaviors. A cursor variable is a variable that references to a cursor. The compiler cannot determine the types until it is ran, so care must be taken to ensure that the cursor result set is handled properly to avoid runtime errors. In ireport, define a report datasource to connect to your oracle database. Ask tom fetch ref cursor to another ref cursor oracle. 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. I have a ref cursor defined as an out parameter and i am trying to get a receiving plsql to accept the ref cursor. Here is the syntax for declaring an updatable cursor.
Select level from dual connect by level is ref cursor. A cursor lets you name the work area, access the information, and process the rows individually. Retrieving data from multiple ref cursors using an. What im trying to do is grab the info from the first cursor, select a few fields out of it and join to some other info and stick the result into a table variable. The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. Even though there is still quite a bit of looping involved, this time, instead of querying the original database tables you will query the collections included in the initial call. Can i see some examples of working ref cursor examples, especially passing a ref cursor between two programs. All public static methods are threadsafe, although instance methods do not guarantee thread.
Ref cursor parameters can be stronglytyped or weaklytyped depending on how they are declared in the procedure or. However, that said i fail to see why you having to select in one stored procedure, to put the data into a global temporary table and then just join. Run operations using ref cursors in oracle database using. Because the oracle ole db provider uses the latest oracle10g technology, oracle ole db offers data access optimizations and access to oracle specific database features, such as support for lobs, plsql stored procedures, and ref cursors. Ref cursor in oracle forms solutions experts exchange. Cursor variables can point to a variety of queries provided the queries have a suitable return type. A variable created based on such a data type is generally called a cursor variable. A ref cursor that specifies a specific return type.
On connection pools, cursor differentiation, and optimal. Id generally go with the former unless there is a good reason to add in a stored procedure layer. 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. Jul 10, 20 sqlplus looked at the ref cursor and saw that it was an open cursor. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. I cant close ref cusor becasue of losing my result set. Resolution when connecting to a 10g database, an oracle 10g client needs to be used in order view the ref cursor results in the procedure editor. To read more about ref cursor i have created a package to explain few different ref cursor examples. Different behavior for ref cursor between oracle 10g and. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql.
This microsoft visual basic example executes a plsql stored procedure that returns two ref cursor parameters, and reads the values using an oracledatareader. Sqlplus looked at the ref cursor and saw that it was an open cursor. In 10g the cursor will contain the expected results but in 11g the cursor will be empty. Ref cursors can often provide greater performance when working with data. Ask tom cursor for loops optimization in 10g oracle. Ireport calling stored procedures jaspersoft community. Cursor variables have several advantages over explicit cursors including. You can open a ref cursor, dynamically or not, and fetch from it within a loop. Meaning that a cursor variable can be opened for any query. In oracle, i have a table called wine and a stored procedure that outputs a cursor based on the wine table. As 2, but hide the query in a view or synonym stored on the local database.
You cannot define the same cursor more than stead you can only use it. Plsql ref cursor performance burleson oracle consulting. For more information, see querying data with plsql. 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. I wrote a stored procedure using ref cursor,and be a data set of reporting service. Plsql cursor variables with ref cursor oracle tutorial. Go for a direct query in the local database using the database link. The name ref cursor can be confusing because a ref cursor variable is not a cursor, but a variable that points to a cursor. Oracle 10g will attach a kgl lock to that statements cursor to hold it open, and create a state object in our session memory that links to the cursor so that we have a short cut to the cursor and dont need to search the library cache for it every time we use it. Declare type empcurtyp is ref cursor return emp%rowtype. Strong plsql ref cursors oracle plsql tips by boobal ganesan. For details, see the book plsql tuning with many oracle ref cursor examples and ref cursor tips. Oct 31, 2009 the lines to start and stop the listener can be removed under oracle 10g release 2, as the dbstart command includes an automatic start of the listener.
We can allocate different storage locations to the cursor when the program runs. Not displaying ref cursor results in procedure editor when. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. If you lose your result set that indicates you are not done with the ref cursor. Another difference is a cursor can be global a ref cursor cannot you cannot define them outside of a procedure function another difference is a ref cursor can be passed from subroutine to subroutine a cursor cannot be. Click start button goto oracle database 10g express edition go to database home page. The screen shot below shows a simple stored procedure that includes a reference cursor as an out parameter. To execute a multirow query, oracle opens an unnamed work area that stores processing information. Plsql procedure returning a refcursor with embedded cursors. Hi tom, i have a procedure which has a string as an in parameter and a ref cursor as an out parameter. Defining cursor variables ref cursor return clause. Net allows developers to take advantage of advanced oracle database functionality, including real application clusters, selftuning statement cache, and fast connection failover.
Another difference is a ref cursor can be returned to a client. You use them when you want to perform a query in one subprogram, and process the results in a different subprogram possibly one written in a different language. Oracle database tips by donald burlesonapril 18, 2015. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database.
Hence you close a ref cursor after you fetch from it. Calling an oracle stored procedure requires the use of a reference cursor as an out parameter. Jun 27, 2012 i doubt something like this would be feasible. Ask tom difference between cursor and a ref cursor oracle. The implicit cursor for loop implicitly array fetches 100 at a time as you can see from his numbers 100 was the sweet spot it is in general, the good number to use for this sort of stuff. This section discusses the following aspects of using the ref cursor datatype and oraclerefcursor objects. Oracleconnection can connect to oracle 8i, 9i, and 10g databases via oci oracle call level interface. Using plsql stored procedures and ref cursors oracle.
I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. This tutorial has been written in french and it would. Once the processing is complete we can use a ref cursor to pass the recordset out to an application. You need to be able to describe any plsql ref cursor in a uniform way across all editions of oracle database from 10g release 1 and newer. I see no need for opening a ref cursor, dynamically or otherwise, so i would just use a regular cursor for loop. Once its fetched all the rows it closes the cursor. Below is an example of how to setup a ref cursor and how to call it from a plsql block. An oraclerefcursor object represents an oracle ref cursor. Because the oracle ole db provider uses the latest oracle10g technology, oracle ole db offers data access optimizations and access to oraclespecific database features, such as support for lobs, plsql stored procedures, and ref cursors. In contrast, explicit cursors are tied to individual queries.
So, if you are just fetching and processing the rows a row at a time, just use the cursor for loop. Declaring ref cursor types and cursor variables passing cursor variables as parameters controlling cursor variables. 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. Ref cursor can be returned from a stored procedure as an oracledatareader via an output parameter defined as oracletype. This tutorial has been written in french and it would be too time consuming to translate it all in english. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. New features in plsql for oracle database 10g release 2 10. The oracle docs specify that the open statement only identifies the result set, but does not retrieve the rows, which happens only with every call to the fetch statement. Different behavior for ref cursor between oracle 10g and 11g when unique index present. You can use with a straight query or a stored procedure and ref cursor. A cursor variable is a pointer that distinguishes the current row in a resultset from a multirow query. Mar 11, 2011 this shouldnt be necessary for java but experience shows that transferring the ref cursor directly fails with oracle database 10g release 1 oracle sometimes throws various invalid cursor errors or provides a null java. First we create a temporary table to hold the data during the processing. Im trying to return two ref cursors from a procedure and having a bit of trouble.
Free oracle magazine subscriptions and oracle white papers. This variable is then looped for processing the returned result set as shown in. Potentially, you need to fetch the ref cursor into transient or persistent storage ill come back to this in a future blog post challenges. Or you can use a regular cursor for loop, which implicitly opens a cursor, not a ref cursor. Toad user is using an older oracle client 9i or earlier. I just open the ref cursor for a query with a where clause equal to in parameter. Resultset and furthermore, its not possible to transfer a ref cursor directly from plsql to a c external. 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. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions, and packages. 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. 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. A cursor variable can be associated with different queries at runtime. In essence, a ref cursor is a pointer or a handle to a result set on the database. It represents a cursor or a result set in oracle database.
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