REF CURSORS HOW TO
The following example shows you how to get a list from an SQL SELECT query which is located in a string and dynamically openend into a REF CURSOR.
For more information see: Hope this helps.Since Oracle 11g there's a method called DBMS_SQL.TO_CURSOR_NUMBER(l_rcursor) which you can use to cast a ref cursor into a cursor and use dbms_sql.describe_columns. Oracle 12c allows implicit statements results, similar to that seen in Transact-SQL, as described here. Oracle 11g allows the two-way conversion between ref cursors to DBMS_SQL cursors, as described here. Which is an example of a weak typed REF CURSOR?Īnd here is an example of a weak typed REF CURSOR declaration that is not associated with any specific structure: Starting from Oracle 9i, you can use SYS_REFCURSOR, which is a predefined weak typed REF CURSOR, to declare a weak REF CURSOR as follows:Ĭan you convert ref cursors to DBMS _ SQL? In essence, a REF CURSOR is a pointer or a handle to a result set on the database. A REF CURSOR is a PL/SQL data type whose value is the memory address of a query work area on the database. 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. Oracle 9i introduced the predefined SYS_REFCURSOR type, meaning we no longer have to define our own REF CURSOR types. Since Oracle 7.3 the REF CURSOR type has been available to allow recordsets to be returned from stored procedures and functions. When to use Ref cursors to return recordsets? Also, the IN clause can’t compare anything with NULL values, but the EXISTS clause can compare everything with NULLs. Conversely, the IN clause is faster than EXISTS when the subquery results is very small. The EXISTS clause is much faster than IN when the subquery results is very large. In other words, a regular cursor can more efficiently retrieve data by using significantly less code. A regular cursor can implicitly array-fetch 100 rows at a time, whereas a ref cursor must use explicit array fetching. The next performance-related advantage of a regular cursor is also an ease-of-use feature. For instance with those SELECT statements that return the result whose datatype matches with the one that you have fixed during cursor’s declaration. Because of fixed return type, strong ref cursors can only be used selectively. What is strong ref cursor in Oracle?Ī ref cursor which has fixed return type is called a Strong Ref Cursor in Oracle Database. These arguments will be substituted by values when the cursor is opened. Then, you put the CURSOR keyword followed by a list of comma-separated arguments ( name datatype ) that defines parameters for the query. … What is ref cursor in PostgreSQL?ĭeclaring cursors PostgreSQL provides you with a special type called REFCURSOR to declare a cursor variable. Is ref cursor can be used for dynamic queries?Īnswer: Here is an example script that performs dynamic SQL and returns the data as a ref cursor. PL/SQL has two forms of REF CURSOR typeS: strong typed and weak typed REF CURSOR. To declare a cursor variable, you use the REF CURSOR is the data type. Different from implicit and explicit cursors, a cursor variable is not tied to any specific query. What is ref cursor and its typeS?Ī cursor variable is a variable that references to a cursor. Cursor data type result set definitions can be defined by providing a row type definition. The property of being strongly or weakly typed is defined when the data type is created. There are two main types of cursor data types: weakly-typed cursor data types and strongly-typed cursor data types. The REF CURSOR can be assigned to other REF CURSOR variables. 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. Can you convert ref cursors to DBMS _ SQL?Ī ref cursor is a variable, defined as a cursor type, which will point to, or reference a cursor result.Which is an example of a weak typed REF CURSOR?.When to use Ref cursors to return recordsets?.Is ref cursor can be used for dynamic queries?.