What is reference cursor in PL SQL?

Introduction to REF CURSORs Using REF CURSOR s 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 PL/SQL data type whose value is the memory address of a query work area on the database.

Hereof, why do we use ref cursor in PL SQL?

Introduction to PL/SQL cursor variables The most important benefit of a cursor variable is that it enables passing the result of a query between PL/SQL programs. To declare a cursor variable, you use the REF CURSOR is the data type. PL/SQL has two forms of REF CURSOR typeS: strong typed and weak typed REF CURSOR .

Additionally, what is SYS ref cursor in Oracle? SYS_REFCURSOR is a predefined weak ref cursor which means we do not have to define it into our code like we did with the explicit weak ref cursor in the previous tutorial. When using SYS_REFCURSOR, you just have to create a cursor variable and nothing else.

Likewise, what is difference between cursor and ref cursor?

2 Answers. A cursor is really any SQL statement that runs DML (select, insert, update, delete) on your database. A ref cursor is a pointer to a result set. A ref cursor is also a cursor, though normally ther term cursor is used when discussing static SQL.

Is ref cursor return?

REF CURSOR is the Oracle data type for a cursor variable. 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.

Is it good to use limit keyword with bulk collect?

No, we cannot use the LIMIT clause with SELECT-INTO statement. So always remember the LIMIT clause can only be used when you are using BULK COLLECT with FETCH-INTO statement. It cannot be used when you are using bulk collect with SELECT-INTO statement.

What is Pragma Autonomous_transaction?

The AUTONOMOUS_TRANSACTION pragma changes the way a subprogram works within a transaction. A subprogram marked with this pragma can do SQL operations and commit or roll back those operations, without committing or rolling back the data in the main transaction. Pragmas are processed at compile time, not at run time.

What is ref cursor example?

PL/SQL Ref Cursors examples. A ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result. 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 can be assigned to other REF CURSOR variables.

What is the use of ref cursor?

Using REF CURSOR s 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 PL/SQL data type whose value is the memory address of a query work area on the database.

What is bulk collect in Oracle?

A bulk collect is a method of fetching data where the PL/SQL engine tells the SQL engine to collect many rows at once and place them in a collection. The SQL engine retrieves all the rows and loads them into the collection and switches back to the PL/SQL engine. All the rows are retrieved with only 2 context switches.

What is strong and weak ref cursor?

Strong ref_cursor will always use to return a value and compiler know the structure during the compile time, but in the weak ref cursor it will not return a value and compiler dosen't know the structure during the compile time.

Do we need to close ref cursor in Oracle?

2) in general Oracle will automatically "deinstantiate" objects when they "GO OUT OF SCOPE". So, when the code that opened the cursor exits, Oracle will close the cursor for you if you forget to do it. This rule applies to several kinds of objects when Oracle is executing your code.

What is cursor in SQL Server?

A SQL cursor is a database object that retrieves data from result sets one row at a time. The cursor in SQL can be used when the data needs to be updated row by row. Contents.

What is mutating error?

A mutating table error (ORA-04091) occurs when a row-level trigger tries to examine or change a table that is already undergoing change (via an INSERT, UPDATE, or DELETE statement). In particular, this error occurs when a row-level trigger attempts to read or write the table from which the trigger was fired.

What is parameterized cursor in PL SQL?

Parameterized cursors (PL/SQL) Parameterized cursors are static cursors that can accept passed-in parameter values when they are opened. The cursor displays the name and salary of each employee in the EMP table whose salary is less than that specified by a passed-in parameter value.

What is the difference between cursor and collections?

A cursor is a compiled SQL program. A cursor variable (in PL/SQL for example) is a pointer/handle for this cursor program in server memory (Shared Pool in the SGA). A collection is a non-scalar/array data structure.

Why do we use bulk collect in Oracle?

What is BULK COLLECT? BULK COLLECT reduces context switches between SQL and PL/SQL engine and allows SQL engine to fetch the records at once. Oracle PL/SQL provides the functionality of fetching the records in bulk rather than fetching one-by-one.

What is an open cursor Oracle?

Open a cursor OPEN cursor_name; In this syntax, the cursor_name is the name of the cursor declared in the declaration section. When you open a cursor, Oracle parses the query, binds variables, and executes the associated SQL statement.

What is bulk bind in Oracle?

Bulk Binds are a PL/SQL technique where, instead of multiple individual SELECT, INSERT, UPDATE or DELETE statements are executed to retrieve from, or store data in, at table, all of the operations are carried out at once, in bulk.

Can ref cursor be used with procedure out parameter?

Using Ref Cursors. The example below uses a ref cursor to return a subset of the records in the EMP table. The following procedure opens a query using a SYS_REFCURSOR output parameter. The cursor can also be referenced as a Java ResultSet.

Why do we use cursors in Oracle?

Cursors are used when the user needs to update records in a singleton fashion or in a row by row manner, in a database table. The Data that is stored in the Cursor is called the Active Data Set. Oracle DBMS has another predefined area in the main memory Set, within which the cursors are opened.

What is Oracle pipeline?

Pipelining enables a table function to return rows faster and can reduce the memory required to cache a table function's results. A pipelined table function can return the table function's result collection in subsets. The returned collection behaves like a stream that can be fetched from on demand.