It is up to the calling code to manage the cursor once it has been opened. Oracle 8i oracle 9i oracle 10g oracle 11g oracle 12c oracle c oracle 18c oracle 19c miscellaneous plsql sql oracle rac oracle apps weblogic linux mysql. 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. Sqlplus looked at the ref cursor and saw that it was an open cursor. Because a ref cursor is a pointer to memory on the server that is returned to the client, the actual data contained in the ref cursor is not initially returned to the client. 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. The ref cursor can be assigned to other ref cursor variables.
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. Even though the example cursor variable is defined, the record can not use it because the cursor. Setting of cursor attributes during cursor execution cycle. Potentially, you need to fetch the ref cursor into transient or persistent storage ill come back to. We will explain different types of cursors with simple examples. I wrote a stored procedure using ref cursor,and be a data set of reporting service. Net as a returnvalue parameter, without using a stored function or procedure. Strong plsql ref cursors oracle plsql tips by boobal ganesan. New features in plsql for oracle database 10g release 2 10. Description an exploration into the different ways you can. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. Restrictions on cursor expressions example of cursor expressions.
Creating aplsql stored procedure that uses ref cursors. For example, you can declare a cursor variable in a plsql host environment such as an oci or proc program, then pass it as an input host variable bind variable to plsql. In case you want to read the previous post oracle cursor basics all examples are tested in oracle 11g release 2 version. Once you load a plsql table an inram array, a ref cursor allows you to reference. To use these examples, you may need to create the oracle tables, and you must create a plsql package and package body. Here is a collection of oracle forms 10g sample dialogs extracted from a complete oracle forms tutorial. The client must request the data contained in the ref cursor after it has opened the ref cursor. In essence, a ref cursor is a pointer or a handle to a result set on the database. This is known as an associative array, and commonly called a plsql table by folks who predate the oraclei documentation that oracle would prefer we forget. Two cursor variables were created over a single ref cursor type declared in the package specification. 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. A cursor variable is a variable that references to a cursor.
Ask tom difference between cursor and a ref cursor oracle. Access to oracle9i database or oracle database 10g. The ref cursor is a data type in the oracle plsql language. A variable created based on such a data type is generally called a cursor variable. The cursor attributes, listed above, are set at different stages of this cycle. To execute a multirow query, oracle opens an unnamed work area that stores processing information. Oracle database plsql users guide and reference 10g release 2 10. Net attributes to custom classes and structs, and to their public fields and properties to convert between udts and custom types, odp. Net can handle multiple ref cursors in a ref cursor, so we tried using embedded cursors, but it did not recognize any cursor from the output and threw some errors. 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. Net 10g release 2, you are now able to easily pass a ref cursor as an input. See also commit in the oracle database sql reference.
A cursor variable can be associated with different queries at runtime. On connection pools, cursor differentiation, and optimal. Different behavior for ref cursor between oracle 10g and 11g when unique index present. If you lose your result set that indicates you are not done with the ref cursor. To read more about ref cursor i have created a package to explain few different ref cursor examples. Reducing network traffic when passing host cursor variables to plsql avoiding errors with cursor variables restrictions on cursor variables using cursor expressions restrictions on cursor expressions example of cursor expressions constructing ref cursors with cursor subqueries overview of transaction processing in plsql using commit in plsql. Creating a plsql stored procedure that uses ref cursors. Net framework data provider for oracle supports the oracle ref cursor data type. Application development tools such as oracle forms, which have a plsql engine, can use cursor variables entirely on the client side. How cursor variables are defined is the topic of the next section. Ask tom fetch ref cursor to another ref cursor oracle.
It allows a user to pass this reference to the same cursor among all the programs that need access to the cursor. Different behavior for ref cursor between oracle 10g and 11g. A ref cursor involves an additional database round trip. There he asked one question as what is the difference between cursor and ref cursor, and when would you appropriately use each of these. The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. I need to return the results to a client application powerbuilder. For example, you can declare a cursor variable in a plsql host environment. Ref cursor in oracle forms solutions experts exchange. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. Dynamic sql with ref cursor burleson oracle consulting. To download free release notes, installation documentation, white papers, or other. Jun 23, 2011 even if an open cursor is not closed, oracle automatically closes it after the execution of its parent block.
Oracle database plsql users guide and reference stanford. Meaning that a cursor variable can be opened for any query. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. Tom, it doesnt make any differenceatleast thats what we thought but we were trying to test oracle s odp. Mar 27, 2005 i have just opened the ref cursor with one sql here for this example but it is built dynamically based on the input values. All public static methods are threadsafe, although instance methods do not guarantee thread. Developers and dbas get help from oracle experts on. When you opt to use a weakly typed cursor, you can anchor it to a plsql structure that is a collection of a plsql record structure. Oracle cursor examples oracle plsql technology blog. For example oracle 19c client libraries can connect to oracle database 11. The table below captures the stage wise value of the status flags. Different from implicit and explicit cursors, a cursor variable is not tied to any specific query. I cant close ref cusor becasue of losing my result set.
Hi tom, feels good that i got a chance to ask you a question. To do this, i understand i must return a ref cursor. Oracle database plsql users guide and reference deiisep. Net allows developers to take advantage of advanced oracle database functionality, including real application clusters, selftuning statement cache, and fast connection failover. This example executes a plsql stored procedure that returns two ref cursor parameters, and fills a dataset with the rows that are returned.
Running a plsql stored procedure usingoracle data provider for. The name ref cursor can be confusing because a ref cursor variable is not a cursor, but a variable that points to a cursor. Different types of cursors in plsql oracle live sql. Introduction to oracle 11g cursors eye on databases. We are currently using oracle 10g version thanks, followup. Here is an example script that performs dynamic sql and returns the data as a ref cursor. Notice the column names are aliased to change their names and doublequoted to force the. Implicit, explicit, cursor for loop example details last updated.
Dec 20, 2016 i hope before knowing about ref cursors you would have a fair idea of what cursors in general are. It represents a cursor or a result set in oracle database. To create cursor variables, you define a ref cursor type, then declare cursor variables of that type. Understanding ref cursors so the cursor never contained any values, it just pointed to a result set that you processed. An oraclerefcursor object represents an oracle ref cursor.
Defining cursor variables ref cursor return clause. We are facing severe performance issues on our server running oracle database 10g release 2 with 2 cpus and 12 gb ram. Ref cursors are one of the most powerful, flexible, and scalable methods for returning query results from an oracle database to a client application. This script is available as part of the sample code download. This variable is then looped for processing the returned result set as shown in. Plsql ref cursor and oraclerefcursor oracle help center. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. From a different procedure, i want to use this return value in some record so i want to declare a cursor. Cursor in, cursor out oracle magazine oracle blogs. The following example shows a simple query opened as a ref cursor, which is subsequently sent to the write procedure. Cursor cursor is one of the fundamental feature of oracle. This stored program could then continue fetching and pass control back to the client. 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. Ref cursors are not result sets but pointers to compiled sql statements.
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. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Plsql cursor variables with ref cursor oracle tutorial. Previous post we have explained detailed about different types of cursors. A cursor variable has datatype ref cursor, and you might see them referred to informally as ref cursors. This scenario can be explained using a simple example shown below.
Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor. Cursor variables are defined using a ref cursor type. Part 12 in a series of articles on understanding and using plsql. In 10g the cursor will contain the expected results but in 11g the cursor will be empty. Strong plsql ref cursors burleson oracle consulting. Here are some things to keep in mind when working with explicit cursors.
Returning multiple ref cursors from oracle procedure using. Hall, one of the worlds top plsql programming gurus, and im referencing his wonderful book plsql tuning where he has many ref cursor examples and ref cursor tips. 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. Plsql ref cursor performance burleson oracle consulting.
Can you show an example of a ref cursor with dynamic sql. A cursor lets you name the work area, access the information, and process the rows individually. 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. 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. To request access to these releases, follow the instructions in oracle support document 1071023. Oracle plsql ref cursors ref cursors a ref cursor or cursor variable is just a reference or a handle to a static cursor. I have been successful returning data from a procedure which returns a single ref cursor using oraclecommand, a dataadapter, and a dataset, but have been having all kinds of issues returning data from a procedure returning multiple ref cursors. I have a function that returns a collection of rows. A ref cursor is a plsql datatype whose value is the address of the memory location of a query work area on the database server. This manuals example scenario is that anyco corp issues each employee various pieces. The first block provides an example of a strongly typed cursor variable, while the following two examples are examples of weakly typed cursor variables. Using plsql stored procedures and ref cursors oracle. Different behavior for ref cursor between oracle 10g and. 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 the wcf service model. The ref cursor will fetch the names of the equipment that have been issued to an employee. Although this reduces the chances of runtime errors. Writing maintainable plsql queries using cursor variables ref cursors what are cursor variables ref cursors. Oracle ref cursor tips oracle database tips by donald burlesonmay 5, 2015 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. The sample code illustrates how simple it is to begin using ref cursors in your. Ref cursor to bulk fetch all column values along with rowids. Oracle products, such as oracle spatial and oracle xml db, use their own complex types frequently. Suggestions, comments, feedbacks and referrals are highly appreciated. 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. Can you explain to me how to convert my example pls.
This behavior is consistent on every 10g or 11g instance ive tried 10. Hence you close a ref cursor after you fetch from it. One can use a ref cursor as target of an assignment, and it can be passed as parameter to other program units. Run operations using ref cursors in oracle database using the. Basically, the procedure opens a reference cursor, updates a table then completes.
The following block uses a cursor for loop to display the last names of all employees in department 10. The procedure accepts 26 input parameters search variable and returns 3 output cursors. I have just opened the ref cursor with one sql here for this example but it is built dynamically based on the input values. I could not understand the technical terms of below paragraph in a clientserver environment, for example, a program on the client side could open and start fetching from the cursor variable, and then pass that variable as an argument to a stored procedure on the server. Free oracle magazine subscriptions and oracle white papers. A ref cursor that specifies a specific return type. Our technologist cleans pools, explores cursor types, and looks for order in table creation. When using the data provider to work with oracle ref cursors, you should consider the following behaviors.
887 77 1347 118 694 1051 1320 754 448 1324 109 271 735 1471 926 1053 301 105 1043 539 442 220 867 846 651 1148 371 613 694 628 1090 217 139 744 447 381 796 929 30 471 57 872 1164 826 1009 307 283 976 744