Run operations using ref cursors in oracle database using the wcf service model. Free oracle magazine subscriptions and oracle white papers. Actually, we have ref cursor as an out variable in the plsql procedure, hence trying to use it dynamically inside the cursor for loop conceptually wrong. I have a lot of legacy functions that return ref cursor. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. For more information, see building a dynamic query with dynamic sql because this statement can use bind variables to make the sql. 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.
What is the difference between a normal cursor and a ref. If you lose your result set that indicates you are not done with the ref cursor. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql. That is the number and type of the columns have to match though not the column names. Here is an example script that performs dynamic sql and returns the data as a ref cursor. Net framework data provider for oracle supports the oracle ref cursor data type. Cursor variables are defined using a ref cursor type.
Calling a stored procedure in oracle which returns a ref cursor requires that parameters have been added to the dbcommandwrapper, the parameter types must be set to oracledbtype. I ask you a favor and i hope you could help me out. Ask tom difference between cursor and a ref cursor oracle. 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. This section discusses the following aspects of using ref cursor and oraclerefcursor objects.
The ref cursor declared in this programs scope is never opened as when it is assigned to the same ref cursor s 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. 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. Run operations using ref cursors in oracle database using. Now we create a print procedure that receives a ref cursor and prints the row data create or.
I just open the ref cursor for a query with a where clause equal to in parameter. So here it is, thanks to juergen in germany for the sample. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. You need to create a function in the database that will return the ref cursor when called, of course you can pass. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time.
Strong plsql ref cursors burleson oracle consulting. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. Strong plsql ref cursors oracle plsql tips by boobal ganesan. This example executes a plsql stored procedure that returns two ref cursor parameters, and fills a dataset with the rows that are returned. This section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects. How cursor variables are defined is the topic of the next section. The variables must match both in number and positionally the columns listed in the ref cursor open statement. Declare type empcurtyp is ref cursor return emp%rowtype. 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. Using plsql stored procedures and ref cursors oracle. A ref cursor being a pointer to an open cursor used to send an open cursor as an out argument to the client app to loop through the record. A ref cursor that specifies a specific return type.
This variable is then looped for processing the returned result set as shown in. I added 2 such columns empid and empname and then override createnewoutputrows as. Ref cursor parameters can be stronglytyped or weaklytyped depending on how they are declared in the procedure or. You can open a ref cursor, dynamically or not, and fetch from it within a loop. The ref cursor is a datatype in the oracle plsql language. This needs to be done using only sql and via a sql join, exists or in operation. When a refcursor is defined with a return type, it is called as a strongly typed static refcursor. Nov 28, 20 reference cursor ref cursor basically, ref cursor is a data type, just like varchar is a variable and holds the value of a string, similarly the ref cursor type holds a cursor. The ref cursor can be assigned to other ref cursor variables. 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. I wrote a stored procedure using ref cursor,and be a data set of reporting service. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. There are two types of cursor variable 1week ref cursor. Calling oracle stored procedures with ref cursors using.
When using the data provider to work with oracle ref cursors, you should consider the following behaviors. The key difference is you can only assign queries that match the return type to a strong cursor. Cursor if using the ms oracle provider to return a resultset in sql server doesnt require or support cursors, and unfortunatley. Defining cursor variables ref cursor return clause. Here i give you an example how i can deal with the problem. Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor. Oracle ref cursor along with out parameters stack overflow. It represents a cursor or a result set in the oracle database. To put it another way, by using ref cursors you have made a rod for your own back.
Or you can use a regular cursor for loop, which implicitly opens a cursor, not a ref cursor. 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. 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. Plsql ref cursor and oraclerefcursor oracle help center. 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 use these examples, you may need to create the oracle tables, and you must create a plsql package and package body. Net to create powerful, flexible, and scalable applications. Strongly typed the ref cursor type is restricted to an individual return type using the return clause. 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. The fetch statement retrieves rows of data from the result set of a multirow query. We can use script component to execute oracle stored procedures with ref cursor as parameters add the output columns to the component. Dynamic sql with ref cursor burleson oracle consulting. It is almost like oracle have implemented only half a job here. Using ref cursor in oracle sql developer stack overflow. Net type for the ref cursor type this section discusses the following aspects of using ref cursor and oraclerefcursor objects obtaining an oraclerefcursor. Refcursor if using the oracle odp provider, or oracletype.
The data is stored in variables or fields that correspond to the columns selected by the query. It represents a cursor or a result set in oracle database. 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. You cannot define the same cursor more than stead you can only use it. Cursors with a defined return type are strongly typed. There are several ways to return query results from an oracle database to a client application, using oracle data provider for.
The ref cursor is a data type in the oracle plsql language. You can fetch rows one at a time, several at a time, or all at once. Far too many enquiries recently about how to hook bip up with a ref cursor. That is the number and type of the columns have to match though not th. I see no need for opening a ref cursor, dynamically or otherwise, so i would just use a regular cursor for loop. Doing a cursor loop fetch and inside doing another cursor loop fetch, is called a nested loop join and sql is significantly better and faster at. This may be a dumb question, but ive never got my head round the strange tablecast. For details, see the book plsql tuning with many oracle ref cursor examples and ref cursor tips. There are two steps required to create a cursor variable. Typically the ref cursor definition and the open for. In essence, a ref cursor is a pointer or a handle to a result set on the database. I cant close ref cusor becasue of losing my result set. Although this reduces the chances of runtime errors.
You need to create a function in the database that will return the ref cursor when called, of course you can pass parameters to the function just like any other function. Getemployees which takes an put put parameter of type ref cursor. Hence you close a ref cursor after you fetch from it. Also the data types must either match or be compatible. Dec 20, 2016 i hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Id like to have a generic method that convert a cursor variable to something what i could query with select statement. For more information, see building a dynamic query with dynamic sql.
We can allocate different storage locations to the cursor when the program runs. To read more about ref cursor i have created a package to explain few different ref cursor examples. Can you show an example of a ref cursor with dynamic sql. Hi tom, i have a procedure which has a string as an in parameter and a ref cursor as an out parameter.