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Oracle Cursor

A cursor is a pointer to a private SQL area that stores information about the processing of a SELECT or DML statements like INSERT, UPDATE, DELETE or MERGE.

Cursor is a mechanism which facilitates you to assign a name to a SELECT statement and manipulate the information within that SQL statement.

How to declare cursor

Syntax

Let's see how to define a cursor called c1. We are using a table name "course" having columns "course_id" and "course_name".

Example

In the above example, the result set of this cursor is all course_id whose course_name matches the variable called name_in.

How to use cursor in a function

Example

Output

Function created.
0.09 seconds

How to open a cursor

After the declaration of the cursor, you have to use the open statement to open the cursor.

Syntax

Example

How to use open cursor in a function

This function specifies how to use the open statement.

Example

Output

Function created.
0.09 seconds

How to fetch rows from cursor

This statement is used after declaring and opening your cursor. It is used to fetch rows from cursor.

Syntax

Parameters

1) cursor_name:It specifies the name of the cursor that you wish to fetch rows.

2) variable_list: It specifies the list of variables that you wish to store the cursor result set in.

Example:

Consider a cursor defined as

Statement used for fetching data

Let's take an example to fetch course_id into the variable called cnumber.

How to close cursor

CLOSE statement is a final step and it is used to close the cursor once you have finished using it.

Syntax

Statement for closing cursor

Example

The following example specifies how to close the cursor.

Cursor within cursor

It is also possible to declare a cursor within a cursor. the following example specifies how to declare a cursor within a cursor.

In this example, there is a cursor named get_tables that retrieves the owner and table_name values. These values are then used in a second cursor called get_columns.

Example

Output

Procedure created.
0.16 seconds

Note: You have to continuously open and close the second cursor each time a new record is retrieved from the first cursor. That way, the second cursor will use the new variable values from the first cursor.

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