How cursor variables are defined is the topic of the next section. 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. Remember that the collection constructed and returned by a streaming table function will consume pga memory, so very large datasets passed into the function via the cursor variable may result in errors. 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. Ask tom difference between cursor and a ref cursor oracle. First we create a temporary table to hold the data during. What is the difference between a normal cursor and a ref. Cursor variables have several advantages over explicit cursors including. The ref cursor is a data type in the oracle plsql language. 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. There are two types of cursor variable 1week ref cursor. In his spare time, he also wrote expert oracle database architecture apress, 2005, 2010, 2014 and effective oracle by design oracle press, 2003, among other books. Can i see some examples of working ref cursor examples, especially passing a ref cursor between two programs.
Use the following format to specify bind information. Using the working example from your notes, your challenge is to write a program that displays all. In stateful applications this could be used to page through results. I have a ref cursor defined as an out parameter and i am trying to get a receiving plsql to accept the ref cursor. 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. Select from tableoracle ref cursor woodward informatics ltd. A ref cursor is not like the scrollable cursor we find in front end languages. How to fetch data from the refcursor oracle community. When the same sql text statement the parent is executed several time in different conditions, you will get several child cursors the parent cursor stores the sql text of the cursor different conditions can be caused by. This section discusses the following aspects of using the ref cursor data type and oraclerefcursor objects. In my example report, i created a package test which contained the following type.
This means, we can read it once and then it is exhausted. When a ref cursor is opened, no data is initially returned to the client. A ref cursor is a reference to a result set that resides in server memory. May, 2016 using oracle ref cursors is the most flexible way to return recordesets from oracle procedures and functions like this. Here is an example script that performs dynamic sql and returns the data as a ref cursor. A ref cursor is a plsql data type whose value is the memory address of a query work area on the database. Cursor in, cursor out oracle magazine oracle blogs. Listing 1 creates a ref cursor and a regular cursor. A ref cursor is a datatype that holds a cursor value in the same way that a varchar2 variable will hold a string value. The ref cursor can be assigned to other ref cursor.
My mentor told me that when querying data i should always use a cursor for loop, even for a single row lookup. Open the ref cursor for the sql and populate the bind variable as you go with the using clause. By using ref cursor we can change the select statement dynamically at runtime which is available in the cursor definition based on some validation. A ref cursor is a plsql data type that represents a pointer to a serverside result set generated by executing a query. There are several ways to return query results from an oracle database to a client application, using oracle data provider for. Free oracle magazine subscriptions and oracle white papers. Refcursor if using the oracle odp provider, or oracletype. If you do not have any oracle software installed on the computer you are running mono but you need to access an oracle database remotely, may i suggest using the oracle instant client. It represents a cursor or a result set in oracle database. A ref cursor is a pl sql data type whose value is the memory address of a query work area on the database. We can allocate different storage locations to the cursor when the program runs.
A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. Cursors explicit cursors contain query results and metadata. Can you show an example of a ref cursor with dynamic sql. Application development tools such as oracle forms, which have a plsql engine, can use cursor variables entirely on the client side. Is it possible to have a plsql procedure that has dynamic sql and uses a ref cursor. It also identifies the rows that meet the criteria in the where clause and join conditions. Pass a cursor variable back to the host environment that called the program. A collection of 19 faqs on working with database objects in plsql. Simple grid report example using basic oracle stored procedure in japser design studio 6.
We are free to use this ref cursor type as parameters for our subroutines and return type for the functions without needing to create them in a package specification, as it is already done by oracle for us. For this we need to define ref cursor type by using following syntax. Ask tom how to get ref cursor from the plsql table. I gave the jdbc oci driver a try, and it is different. A ref cursor that specifies a specific return type. Strong ref cursor and weak ref cursor for the strong ref cursor the returning columns with datatype and length need to be known at compile time. Then, explicitly open the reference cursor into the variable. The following plsql calls would work with any oracle jdbc driver. Oracle tutorialonlinetrainingplsql ref cursor part.
Dec 05, 2006 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. Our technologist takes another look at oracle database 11g. You can also redistribute the oracle instant client for free. So the java program is calling the oracle function to get the data. Cursor variables give you easy access to centralized data retrieval. A cursor variable is a pointer that distinguishes the current row in a resultset from a multirow query. Last issue, i wrote about some new oracle database 11g features, and i continue that coverage in this issue, focusing on my favorite procedural language, plsql. Although this reduces the chances of runtime errors. A new program unit window will popup, where you need to specify the return type of the ref cursor strongly typed ref cursor. A ref cursor essentially encapsulates the results of a query.
You cannot define the same cursor more than stead you can only use it. Create a record structure to store rows of the reference cursor in an ordinary fetch, or a record structure and associative array collection data type to store a set of rows of the reference cursor. When using the data provider to work with oracle ref cursors, you should consider the following behaviors. Over the years i have experimented with a lot else too, even resorting to thoroughly rtfm from oracle. Oracle concepts software support remote s upport development implementation consulting staff consulting prices help wanted. Metadata for resultsets and ref cursors is available in a resultset property. Using plsql stored procedures and ref cursors oracle. When you open a cursor, plsql executes the query for that cursor. He says its the easiest way to fetch data, and oracle database automatically optimizes it in oracle database 10g and above. Sadakar pochampalli hi, in this post you will see how to work with a basic oracle stored procedure. Net configuration file needs to define the ref cursor bind and metadata information.
In your code, you are just opening the cursor but not fetching from it. 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. Cursor variables are defined using a ref cursor type. For the weak ref cursor the structure does not need to be known at compile time. Anchor the cursor statement to a table or view in the database catalog.
Oraoledb returns a rowset for the ref cursor bind variable. 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. Declare type empcurtyp is ref cursor return emp%rowtype. You can declare a reference cursor type and a cursor variable based on that type. Run operations using ref cursors in oracle database using. With simple update statement we can update only simple data but with cursor we can update data with reference.
Calling oracle stored procedures with ref cursors using the. The easy way to send a ref cursor to plsql with odp. A ref cursor is an oracle plsql data type that represents a pointer to a result set in the oracle database. The open does not actually retrieve any of these rows. Plsql ref cursor and oraclerefcursor oracle help center. My attempts to parameterize the oracle sql for daily input have been confounded by what i understand to be an oracle sql server incompatability on including parameters or variables in a sql command and the 4000 character limit on.
Oracle database makes it easy to execute sql statements and plsql blocks. Developers and dbas get help from oracle experts on. Afaik, there is no way of getting metadata from a ref cursor directly from plsql. It is up to the calling code to manage the cursor once it has been opened. Strongly typed the ref cursor type is restricted to an individual return type using the return clause. Tom, it doesnt make any differenceatleast thats what we thought but we were trying to test oracle s odp. There he asked one question as what is the difference between cursor and ref cursor, and when would you appropriately use each of these. Cursor can be attached to only one query while ref cursor can be used to associate multiple queries at run time. It allows a user to pass this reference to the same cursor among all the programs that need access to the cursor. To access data returned by a query, you use cursors and ref cursors. Because there is no predefined data type for ref cursor in the ole db specification, the consumer must not bind this.
Then you define a select statement that the ref cursor will represent using a bind variable in the place of the dynamic table name you get from the outer cursor. Getting data from an oracle sp ref cursor i have an oracle 11 table which is the source for a sql server 2008 table. The ref cursor can be assigned to other ref cursor variables. A ref cursor is a variable, defined as a cursor type.
Net framework data provider for oracle supports the oracle ref cursor data type. Oracle posters oracle books oracle scripts ion exceldb. To read more about ref cursor i have created a package to explain few different ref cursor examples. The oracle instant client is far more easier to install than the normal oracle client software. The example below uses a ref cursor to return a subset of the records in the emp table.
How to write ref cursor query in oracle reports solutions. Invoke functions and procedures with ref cursors in oracle database using biztalk server. To access data returned by a query, you define cursors and ref cursors where. From the data model editor in oracle reports, choose the ref cursor query icon from the tool pallet. For a null out cursor, you get a resultset object with empty metadata. In his 22 years at oracle, tom kyte started the ask tom question and answer site and was the sites sole proprietor for almost 15 years. Simple grid report example using basic oracle stored. In contrast, explicit cursors are tied to individual queries. This may be a dumb question, but ive never got my head round the strange tablecast.
A cursor is a cursor, by any other name and smells just as sweet. Cursor variables can point to a variety of queries provided the queries have a suitable return type. 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. Column names in an empty oracle ref cursor stack overflow. Plsql procedural languagestructured query language is oracle corporations procedural extension for sql and the oracle relational database. 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. Invoke functions and procedures with ref cursors in oracle. Oracle database makes building such functions easy, through its implementation of plsql cursor variables and the cursor expression. Defining cursor variables ref cursor return clause. Oracle plsql ref cursors ref cursors a ref cursor or cursor variable is just a reference or a handle to a static cursor. Dynamic sql with ref cursor burleson oracle consulting. We will now look at how we can use visual basic to call our procedures and read the records stored in the ref cursor. Hi tom, feels good that i got a chance to ask you a question. Oracle provider for ole db allows consumers to execute a plsql stored procedure with an argument of ref cursor type or a stored function returning a ref cursor value.
Net to create powerful, flexible, and scalable applications. 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. Its important to know when not to use cursor for loops. Run operations using ref cursors in oracle database using the. 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. The cursor variable is specified as an in out parameter so that the result set is made available to the caller of the procedure. Clear answers are provided with tutorial exercises on defining, opening, and closing cursors, looping through cursors, defining and using cursor. A ref cursor or cursor variable data type contains a reference to a cursor. The add element uses namevalue attributes to specify ref cursor information. Specifying ref cursor bind and metadata information in the. Returning ado resultsets using plsql and cursor variables.
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