A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. We can allocate different storage locations to the cursor when the program runs. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions. Oracle database plsql language reference, 11g release 2 11. 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. Declare type empcurtyp is ref cursor return emp%rowtype. Oracle fusion middleware installation guide for oracle portal, forms, reports and discoverer.
Cursors returned in this fashion should not be closed. A ref cursor is a datatype that holds a cursor value in the same way that a varchar2 variable will hold a string value a ref cursor can be opened on the server and passed to the client as a unit rather than fetching one row at a time. First, my question is passing ref cursor variables as actual parameters valid in oracle. Oracle cddrepository software is referred to as the dictionary. One can use a ref cursor as target of an assignment, and it can be passed as parameter to other program units. How to use ref cursor example a ref cursor is basically a data type. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. However, the uninitialized oraclerefcursor can be reassigned to another ref cursor.
There are sample also, that demonstrates this method. Returning a ref cursor from a oracle function stack overflow. Oracle database plsql language reference oracle docs. Oracle is a registered trademark, and hot standby, logminer for rdb, oracle cddrepository, oracle codasyl dbms, oracle expert, oracle rdb, oracle rmu. The primary advantage of using cursor variables is their capability to pass result sets between sub. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. A variable created based on such a data type is generally called a cursor variable. In this case, oracle will close the cursor as soon as it is out of scope. Crystal report using ref cursor ole db failed to retrieve. Returning ado resultsets using plsql and cursor variables. In this manual, oracle rdb refers to oracle rdb for openvms. Ref cursor as in bind variable see the github example.
The value is either an integer specifying the number of elements to allocate or it is a list and the number of elements allocated is drawn from the size of the list. In order to do this some generic packages were created to create the xml based on the content of a refcursor. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql. Net documentation describes a method for passing refcursor, obtained from plsql to another plsql procedure.
The query planner spends less time planning the query and starts returning results faster, but this could diminish performance if more than 10% of the results are retrieved. Run operations using ref cursors in oracle database using. The cursor can be opened on the server and then passed to the referenced to the same cursor among all the programs that need the cursor access. To put it another way, by using ref cursors you have made a rod for your own back. Oracle ole db provider stored procedure ref cursor. Oracle database sql language reference oracle database plsql language reference. Reference cursor as input parameter to a procedure i have a requirement where i should pass cursor variable as input parameter to a procedure and fetch data from that in the procedure. Using ref cursors to return recordsets since oracle 7. When declaring the ref cursor in an oracle package, the ref cursor may be strongly bound or it may be weakly bound. Free oracle magazine subscriptions and oracle white papers. The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. The ref cursor is a data type in the oracle plsql language. What is the difference between a normal cursor and a ref.
Each time you open the cursor, you can pass different arguments to the cursor, which results in different result sets. Cursor variables are defined using a ref cursor type. Plsql users guide and reference oracle help center. Ref cursors are represented through the oraclerefcursor odp. Passing a ref cursor to a stored procedure oracle community. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. The above syntax shows how to create a new ref cursor type, we need to create a ref cursor declaration with a return clause, which defines the query must rerun rows at runtime. A ref cursor that specifies a specific return type.
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. Ref cursor s are represented through the oraclerefcursor odp. Security enhancements in the previous oracle database releases, the oracle jdbc driver has supported several security mechanisms including. A strongly bound ref cursor is bound with the same structure that is used by the outputted select statement in the oracle stored procedure.
See also commit in the oracle database sql reference. 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. Implicit results permit a python program to consume cursors returned by a plsql block without the requirement to use out ref cursor parameters. If you know the internal structure of the ref cursor, you can loop through it and output the contents using plsql.
Strongly typed the ref cursor type is restricted to an individual return type using the return clause. Plsql ref cursor and oraclerefcursor oracle help center. Oracle ole db provider stored procedure ref cursor errror. Return a list of cursors which correspond to implicit results made available from a plsql block or procedure without the use of out ref cursor parameters. How cursor variables are defined is the topic of the next section. It may include documentation of features of mysql versions that have not yet been released. Fusion middleware oracle reports users guide to building reports. Also the data types must either match or be compatible. This sample are given in pdf documentation only odp. It requires both the oracle client and oracle database to be 12. I could not get either to work with the oracle ole db provider. A cursor variable can be associated with different queries at runtime. This microsoft visual basic example executes a plsql stored procedure that returns a ref cursor parameter, and reads the value as an oracledatareader.
The problem is when there are no rows in the cursor suppose the table doesnt have any rows and we are reading it into a cursor and from the front end i. It is almost like oracle have implemented only half a job here. The oracle rdb documentation set to which this manual belongs often refers to the following oracle corporation products by their abbreviated names. Thanks for the comments while this is indeed pretty simple for a sql statement like this, it gets substantially more messy when im doing a complex query covering multiple tables. Although this reduces the chances of runtime errors.
For this we need to define ref cursor type by using following syntax. By using ref cursor we can change the select statement dynamically at runtime which is available in the cursor definition based on some validation. By default, postgresql assumes that only the first 10% of the results of cursor queries will be fetched. This example executes a plsql stored procedure that returns two ref cursor parameters, and fills a dataset with the rows that are returned. The variables must match both in number and positionally the columns listed in the ref cursor open statement. Run operations using ref cursors in oracle database using the wcf service model. Hi tom, i have a procedure which has a string as an in parameter and a ref cursor as an out parameter. Querying data with plsql selecting at most one row select into statement selecting multiple rows bulk collect clause looping through multiple rows cursor for loop performing complicated query processing explicit cursors cursor for loop sql cursor for loop. This is a dbicompliant oracle driver based on the oci.
The ref cursor can be assigned to other ref cursor variables. Xmltype, refcursor and renaming row and rowset tags the project that im currently involved in uses xml to send data to a reporting engine which parses the xml and creates a pretty pdf report. An oraclerefcursor object can be bound to a ref cursor after a command execution. Forms upgrading oracle forms 6i to oracle forms 11g. You cannot define the same cursor more than stead you can only use it. Section passing a ref cursor to a stored procedure. To use these examples, you may need to create the oracle tables, and you must create a plsql package and package body. We will now look at how we can use visual basic to call our procedures and read the records stored in the ref cursor. If the connection is closed or returned to the connection pool, the oraclerefcursor is placed in an uninitialized state and no operation can be carried out from it.
Defining cursor variables ref cursor return clause. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Demos, syntax, and example code of oracle plsql strongly typed and weakly typed ref cursors. Create the following oracle package on the oracle server. Using plsql stored procedures and ref cursors oracle. Using plsql stored procedures and ref cursors oracle docs. Oracle database plsql users guide and reference oracle docs. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. The following shows the syntax of a declaring a cursor with parameters. 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. However, i must say that it should be a good habit always to close it explicitly. Pingte title oci based oracle database interface for r description oracle database interface dbi driver for r.
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