Using plsql stored procedures and ref cursors oracle docs. Cursor variables are defined using a ref cursor type. So now we have something in an structure that sql understands, we should be able to query directly from it. Using plsql stored procedures and ref cursors oracle. The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. The ref cursor is a datatype in the oracle plsql language. The ref cursor can be assigned to other ref cursor variables.
Procedure that outputs a dynamic plsql cursor question. Ref cursor in oracle forms solutions experts exchange. Also the data types must either match or be compatible. The variables must match both in number and positionally the columns listed in the ref cursor open statement. How cursor variables are defined is the topic of the next section. 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.
Syntax of ref cursor the following is the syntax of. Cursor if using the ms oracle provider to return a resultset in sql server doesnt require or support cursors, and unfortunatley. Ref cursors are represented through the oraclerefcursor odp. Once a cursor variable is opened with a query statement, it will have the same attributes as a normal cursor and it can be used in the same way a normal cursor too.
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. If you dont already have a table named emp, create that as well and insert a row of test data. A ref cursor is a variable, defined as a cursor type, which will point to. If you know the internal structure of the ref cursor, you can loop through it and output the contents using plsql. Many of the crossreferences from this book to other books have been made. Now you can see the ref cursor results in another window as shown below. It is almost like oracle have implemented only half a job here. To put it another way, by using ref cursors you have made a rod for your own back. Therefore, the client must be connected to the database during the lifetime of the ref cursor in order to access it. How to return a ref cursor as an output parameter from a. You do not need to bind the ref cursor as an output parameter when you prepare the callable statement.
How to use ref cursor example a ref cursor is basically a data type. Update some data inside tablea from inside the stored procedure. Ref cursors, as a plsql data type offers a pointerlike address that is an effect a memory location of a query address space. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. The microsoft biztalk adapter for oracle database supports ref cursor parameters in procedures, functions, and packages. Another difference is a ref cursor can be returned to a client. Ref cursor parameters can be stronglytyped or weaklytyped depending on how they are declared in the procedure or. Cursor attributes reveal the cursor related information and status. For developers, implicit cursor appears to be an abstract concept. There are two steps required to create a cursor variable. 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.
There are two types of cursor variable 1week ref cursor. A fetch statement retrieves rows one at a time from the result set of a multirow. 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. Ref cursor is the oracle data type for a cursor variable. Cursor expressions as arguments to functions called from sql. 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. Creating a plsql stored procedure that uses ref cursors. Choose the last radio button load into grid from memory strong and weak test ref cursor from toad step 3. Only thing which is physically available and visible to them is the cursor status flags and information. When calling a stored procedure that returns a ref cursor, different behavior is seen in 10. The oracle driver converts the ref cursor data to a result set that can be returned using getresultset or getmoreresults. A variable created based on such a data type is generally called a cursor variable. You need to fetch the ref cursor into transient memory or persistent storage normal or global temporary table.
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. Next a procedure is defined to use the ref cursor and the temporary table. I see no need for opening a ref cursor, dynamically or otherwise, so i would just use a regular cursor for loop. It allows a user to pass this reference to the same cursor among all the programs that need access to the cursor. Or you can use a regular cursor for loop, which implicitly opens a cursor, not a ref cursor. We can allocate different storage locations to the cursor when the program runs.
You can open a ref cursor, dynamically or not, and fetch from it within a loop. For more information, see oracle database sql reference. Refcursor if using the oracle odp provider, or oracletype. Hello, i am wondering if anyone in this community knows the shorter way to return an oracle ref cursor to a. Although this reduces the chances of runtime errors. The primary advantage of using cursor variables is their capability to pass result sets between sub. A ref cursor refers to a memory address on the database. Because jdbc does not support a cursor variable data type, the oracle driver returns ref cursor output parameters and return values to the application as result sets.
It is up to the calling code to manage the cursor once it has been opened. Ask tom fetch ref cursor to another ref cursor oracle. This book includes scripts and tools to hypercharge oracle 11g performance and. It represents a cursor or a result set in oracle database. Different behavior for ref cursor between oracle 10g and. Cursor variables give you easy access to centralized data retrieval. Ive created an html form where the user can enter any combination of three values to retrieve results from the wine table. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Plsql users guide and reference oracle help center. Sqlplus looked at the ref cursor and saw that it was an open cursor. A cursor variable can be associated with different queries at runtime. 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. What i didnt like is the fact that i had to write a ton of code to just see the output. In essence, a ref cursor is a pointer or a handle to a result set on the database.
What is the difference between a normal cursor and a ref. To use these examples, you may need to create the oracle tables, and you must create a plsql package and package body. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. I have an oracle package with a procedure that has a in out reference cursor. Working with oracle ref cursors and stored procedures is an often used mechanism when working with oracle data sources. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql.
Strongly typed the ref cursor type is restricted to an individual return type using the return clause. The ref cursor is a data type in the oracle pl sql language. 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. Oracle database plsql users guide and reference oracle docs. When all rows have been fetched, the ref cursor is closed and the sql table structure is passed back from the function. In oracle, i have a table called wine and a stored procedure that outputs a cursor based on the wine table. 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. Calling oracle stored procedures with ref cursors using. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure.
Effective ef with oracle stored procedures with ref curs. The address space is much like a standard result set or dataset in. Defining cursor variables ref cursor return clause. 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. Ask tom difference between cursor and a ref cursor oracle. Demos, syntax, and example code of oracle plsql strongly typed and weakly typed ref cursors. Free oracle magazine subscriptions and oracle white papers. Once its fetched all the rows it closes the cursor. Execute an oracle function that returns a reference cursor. Introduction to oracle 11g cursors eye on databases. But the problem i see is not that your ref cursor is too big a ref cursor is not a statement but a result set, but the sql statement in your example will be bigger than the allowable 64k. 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.
You cannot define the same cursor more than stead you can only use it. The example below uses a ref cursor to return a subset of the records in the emp table. Run operations using ref cursors in oracle database using. This example executes a plsql stored procedure that returns two ref cursor parameters, and fills a dataset with the rows that are returned. 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. The ref cursor is a data type in the oracle plsql language. A ref cursor or cursor variable is just a reference or a handle to a static cursor. A ref cursor that specifies a specific return type.
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