The cursor for loop is an elegant and natural extension of the numeric for loop in plsql. Update some data inside tablea from inside the stored procedure. 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. I see no need for opening a ref cursor, dynamically or otherwise, so i would just use a regular cursor for loop. In similar manner you can test any ref cursor within package. 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. You can fetch rows one at a time, several at a time, or all at once. Ask tom fetch ref cursor to another ref cursor oracle. Thanks sridhar, my problem was not too much of passing.
Dec 20, 2016 i hope before knowing about ref cursors you would have a fair idea of what cursors in general are. When a refcursor is defined with a return type, it is called as a strongly typed static refcursor. A ref cursor that specifies a specific return type. 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. To put it another way, by using ref cursors you have made a rod for your own back. Cursor variables are defined using a ref cursor type. Different behavior for ref cursor between oracle 10g and. Using ref cursor in oracle sql developer stack overflow. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. Another difference is a ref cursor can be returned to a client.
Select from tableoracle ref cursor woodward informatics ltd. Irrespective of the return clause, each type that you define is a new separate datatype. Choose the last radio button load into grid from memory strong and weak test ref cursor from toad step 3. A fetch statement retrieves rows one at a time from the result set of a multirow. It represents a cursor or a result set in oracle database.
If the cursor is moved to a package, you will have the now necessary close already in place. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. This readwrite attribute specifies the number of rows to fetch at a time internally and is the default number. Declare type empcurtyp is ref cursor return emp%rowtype. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql. 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 just open the ref cursor for a query with a where clause equal to in parameter. There are two steps required to create a cursor variable. Now you can see the ref cursor results in another window as shown below. How cursor variables are defined is the topic of the next section. Create ref cursor queries that will use the ref cursors. Defining cursor variables ref cursor return clause. Dynamic sql with ref cursor burleson oracle consulting.
The variables must match both in number and positionally the columns listed in the ref cursor open statement. 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. 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. Return values from a plsql table into a ref cursor. The ref cursor interface, on the other hand, simply takes as input the owner to search for and returns a single ref cursor that can select as many columns as you like. This rule applies to several kinds of objects when oracle is. Now, let s move onto the package bodies for the implementation. The exit point for the cursor as a context manager. Strong plsql ref cursors oracle plsql tips by boobal ganesan. This section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects. Stored procedures or functions as well as packaged procedures or functions can return cursor variables. It is almost like oracle have implemented only half a job here. Run operations using ref cursors in oracle database using. Run operations using ref cursors in oracle database using the wcf service model.
This method is an extension to the db api definition. When i execute the fetch, i get ora01001 invalid cursor. To create a ref cursor query, you first create a package spec that defines the ref cursor. And if it is local, then including a close statement will also show other developers and your manager that you are paying attention.
With a cursor for loop, the body of the loop is executed for each row returned by the query. Different behavior for ref cursor between oracle 10g and 11g. 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. The steps in this section will help you create package specs that define ref cursors. Now we create a print procedure that receives a ref cursor and prints the row data create or. Pkg2 used a to declare b and passed b to procedure of pkg1 while referencing the main problem, i was assuming i will get back the members of a. The data is stored in variables or fields that correspond to the columns selected by the query. When calling a stored procedure that returns a ref cursor, different behavior is seen in 10. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions, and packages. So, when the code that opened the cursor exits, oracle will close the cursor for you if you forget to do it. The ref cursor is a data type in the oracle plsql language. Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor. Pkg1 declared a ref type cursor a, declared a cursor test and opened it for ouput.
One can use a ref cursor as target of an assignment, and it can be passed as parameter to other program units. Also the data types must either match or be compatible. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. You can open a ref cursor, dynamically or not, and fetch from it within a loop. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. Here is an example script that performs dynamic sql and returns the data as a ref cursor. Typically the ref cursor definition and the open for. The cursor variable then acts as a pointer to the query or select thus opened.
In essence, a ref cursor is a pointer or a handle to a result set on the database. I have a forms 6i that makes a call to the function, with the intent of fetching the data associated with the ref cursor. Ref cursor parameters can be stronglytyped or weaklytyped depending on how they are declared in the procedure or. With a numeric for loop, the body of the loop executes once for every integer value between the low and high values specified in the range. We can allocate different storage locations to the cursor when the program runs. Using plsql stored procedures and ref cursors oracle. A variable created based on such a data type is generally called a cursor variable. To read more about ref cursor i have created a package to explain few different ref cursor examples. Or you can use a regular cursor for loop, which implicitly opens a cursor, not a ref cursor. Ask tom difference between cursor and a ref cursor oracle.
The function creates dynamic sql and initiates the open of the cursor. Can you show an example of a ref cursor with dynamic sql. Strongly typed the ref cursor type is restricted to an individual return type using the return clause. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions. The ref cursor can be assigned to other ref cursor variables.
The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. Say the business requirement changes so that the data should be displayed in a different order. The entry point for the cursor as a context manager. Oracle jdbc extensions using java database connectivity. 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. Free oracle magazine subscriptions and oracle white papers. A ref cursor is a datatype that holds a cursor value in the same way that a varchar2 variable will hold a string value. Strong plsql ref cursors burleson oracle consulting. It is a good practice to use strongly typed cursor variable types this ensures that columns returned by a query will match the return type of the cursor. A cursor variable can be associated with different queries at runtime.
Although this reduces the chances of runtime errors. Hi tom, i have a procedure which has a string as an in parameter and a ref cursor as an out parameter. A variable can defined of the ref cursor type and then a query can be opened for it. I am using several package functions to return ref cursors to a java front end. This rule applies to several kinds of objects when oracle is executing your code. Run operations using ref cursors in oracle database using the. Dec 18, 2016 it is almost like oracle have implemented only half a job here. The fetch statement retrieves rows of data from the result set of a multirow query. 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. A ref cursor is a weakly typed cursor type that identifies a cursor variable.
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