Dec 20, 2016 i hope before knowing about ref cursors you would have a fair idea of what cursors in general are. Installation guides and general oracle database 11g documentation are here. Oracle associates every select statement with a cursor to hold the query information in this context area. However, i must say that it should be a good habit always to close it explicitly. What im trying to do is grab the info from the first cursor, select a few fields out of it and join to some other info and stick the result into a table variable. How cursor variables are defined is the topic of the next section. Im trying to return two ref cursors from a procedure and having a bit of trouble. 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. Can you show an example of a ref cursor with dynamic sql. Oracle database 11g release 2 for microsoft windows x64.
What is the difference between a normal cursor and a ref. To create a cursor variable, define a ref cursor type, and then declare the cursor variable to be of that type. Ref cursor in oracle forms solutions experts exchange. The name ref cursor can be confusing because a ref cursor variable is not a cursor, but a variable that points to a cursor. Download and unzip both files to the same directory. 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. You can describe the query, fetch from it, get the ith column, etc. Introduction to oracle 11g cursors eye on databases. I have very limited permissions on the database and as such all i can do is call procedures that reside in packages. The ref cursor is a data type in the oracle plsql language.
Here is the syntax for declaring an updatable cursor. Cursor expressions as arguments to functions called from sql. If you lose your result set that indicates you are not done with the ref cursor. Another difference is a ref cursor can be returned to a client. A variable created based on such a data type is generally called a cursor variable. Defining cursor variables ref cursor return clause. Declaring a cursor variable creates a pointer, not an item.
A ref cursor is a variable, defined as a cursor type. A cursor variable is like a c or pascal pointer, which holds the address of an item instead of the item itself. Visit plsql challenge to read a complete explanation of the answers to this quiz. For more information, see building a dynamic query with dynamic sql because this statement can use bind variables to make the sql. Determining whether to use plsql native compilation. Listing 1 creates a ref cursor and a regular cursor. Free oracle magazine subscriptions and oracle white papers. The article describes the oracle cursors and their usage. We will explain different types of cursors with simple examples. 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.
Example 711 procedure vulnerable to sql injection through data type. Or you can use a regular cursor for loop, which implicitly opens a cursor, not a ref cursor. Plsql ref cursor performance burleson oracle consulting. Meaning that a cursor variable can be opened for any query. A ref cursor that specifies a specific return type. This needs to be done using only sql and via a sql join, exists or in operation. An oraclerefcursor object represents an oracle ref cursor. Using ref cursor s is one of the most powerful, flexible, and scalable ways to return query results from an oracle database. Strongly typed the ref cursor type is restricted to an individual return type using the return clause. We can allocate different storage locations to the cursor when the program runs. Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor. 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. You cannot define the same cursor more than stead you can only use it. Jun 23, 2011 the memory location to which it points is known as context area.
You can open a ref cursor, dynamically or not, and fetch from it within a loop. Dynamic sql with ref cursor burleson oracle consulting. Now we create a print procedure that receives a ref cursor and prints the row data create or. In case you want to read the previous post oracle cursor basics all examples are tested in oracle 11g release 2 version. I see no need for opening a ref cursor, dynamically or otherwise, so i would just use a regular cursor for loop. Weve got a function that, based on dynamically generated query, returns a ref cursor variable. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. Developers and dbas get help from oracle experts on. How do i see the contents of the refcursor if i dont know the no of columns it is returning. It represents a cursor or a result set in oracle database. On connection pools, cursor differentiation, and optimal. Pl sql ref cursor performance burleson oracle consulting. Oracle cursor examples oracle plsql technology blog.
Review the certification matrix for this product here. 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. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. 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.
How do i see the contents of the refcursor if i dont know the no of columns it is returning plsql thanks koshal. 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. In essence, a ref cursor is a pointer or a handle to a result set on the database. However, it seems politically insensitive to use that language even though oracle published it as such. Ask tom how do i see the contents of the refcursor if i d. A cursor variable can be associated with different queries at runtime. However, it fails if the resulting string is longer than 32k. To create cursor variables, you define a ref cursor type, then declare cursor variables of that type. Here is an example script that performs dynamic sql and returns the data as a ref cursor. Two out ref cursors fetches around 70,000 records and for each record again some internal procedures gets called we have done some changes to queries used to fetch these ref cursors data. This section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects.
Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. I have a ref cursor defined as an out parameter and i am trying to get a receiving plsql to accept the ref cursor. Previous post we have explained detailed about different types of cursors. The primary advantage of using cursor variables is their capability to pass result sets between sub programs like stored procedures, functions. I cant close ref cusor becasue of losing my result set. 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. For details, see the book plsql tuning with many oracle ref cursor examples and ref cursor tips. Dynamic ref cursor with dynamic fetch an 11g version sometimes there is a problem as follows. Application development tools such as oracle forms, which have a plsql engine, can use cursor variables entirely on the client side. 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. Stack overflow for teams is a private, secure spot for you and your coworkers to find and share information.
To read more about ref cursor i have created a package to explain few different ref cursor examples. 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. Net framework data provider for oracle supports the oracle ref cursor data type. This example demonstrates how to define and open a ref cursor variable, and then pass it as a procedure parameter. In essence, a ref cursor allows you to store the result of a bulk collect from a table or any pl sql cursor return set into a pl sql table ram array and then reference the array with the ref cursor as a pointer. As other answers pointed out they are memory structures used to temporarily store and iterate through a query result set in plsql. Declare type empcurtyp is ref cursor return emp%rowtype. First, a ref cursor can be dynamically opened and defined at runtime, in contrast to a regular cursor, which is static and defined at compile time. Although this reduces the chances of runtime errors. Using plsql stored procedures and ref cursors oracle docs. A cursor variable is a variable that references to a cursor.
Oraclerefcursor static methods are listed in table 1128. I wrote a stored procedure using ref cursor,and be a data set of reporting service. Now we want to use this ref cursor variable in our procedure, but we dont know the record structure. Plsql cursor variables with ref cursor oracle tutorial. 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. Ask tom fetch ref cursor to another ref cursor oracle. There are two types of cursor variable 1week ref cursor. Ask tom refcursors vs pipelined functions 11g oracle. Different from implicit and explicit cursors, a cursor variable is not tied to any specific query.
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. I need some inputs on since procedures returns control back when both these cursors sqls gets executed holding around 70,000 records. Oracle provides the for update clause of the select statement in an updatable cursor to perform this kind of locking mechanism. 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. When using the data provider to work with oracle ref cursors, you should consider the following behaviors. Tuning dynamic sql with execute immediate statement and cursor variables. How to fetch data from the refcursor oracle community. I hope before knowing about ref cursors you would have a fair idea of what cursors in general are.
I am working on a system where oracle 11g is the back end database. Can i see some examples of working ref cursor examples, especially passing a ref cursor between two programs. Sometimes, you want to lock a set of rows before you can update them in your program. Cursor variables are defined using a ref cursor type. Using plsql stored procedures and ref cursors oracle.
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