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What is fetch in PL SQL?

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What is fetch in PL SQL?

The FETCH statement retrieves rows of data from the result set of a multi-row query. You can fetch rows one at a time, several at a time, or all at once. The data is stored in variables or fields that correspond to the columns selected by the query.

What is fetch in Oracle?

FETCH statement is used in Oracle to retrieve row or rows of data from the result set of a multi row query as FETCH statement has the ability to retrieve one row of data at a instance, more than one row of data or even all rows of data present in the result set thereby allowing the developer to control the percentage …

How do I use cursor to fetch multiple records?

Procedure

  1. Specify the cursor using a DECLARE CURSOR statement.
  2. Perform the query and build the result table using the OPEN statement.
  3. Retrieve rows one at a time using the FETCH statement.
  4. Process rows with the DELETE or UPDATE statements (if required).
  5. Terminate the cursor using the CLOSE statement.

How do you open fetch and close a cursor in PL SQL?

Before using an explicit cursor, you must declare it in the declaration section of a block or package as follows:

  1. CURSOR cursor_name IS query;
  2. OPEN cursor_name;
  3. FETCH cursor_name INTO variable_list;
  4. CLOSE cursor_name;
  5. cursor_name%attribute.

What does closing a cursor do?

After all rows have been retrieved from the result set that is associated with a cursor, the cursor must be closed. The result set cannot be referenced after the cursor has been closed. However, the cursor can be reopened and the rows of the new result set can be fetched.

What are the steps for using a cursor?

There are four steps in using an Explicit Cursor.

  1. DECLARE the cursor in the declaration section.
  2. OPEN the cursor in the Execution Section.
  3. FETCH the data from cursor into PL/SQL variables or records in the Execution Section.
  4. CLOSE the cursor in the Execution Section before you end the PL/SQL Block.

Can cursor operate multiple rows?

The multiple-row FETCH statement can be used with both serial and scrollable cursors. The operations used to define, open, and close a cursor for a multiple-row FETCH remain the same. Only the FETCH statement changes to specify the number of rows to retrieve and the storage where the rows are placed.

How do I run a cursor?

To use cursors in SQL procedures, you need to do the following:

  1. Declare a cursor that defines a result set.
  2. Open the cursor to establish the result set.
  3. Fetch the data into local variables as needed from the cursor, one row at a time.
  4. Close the cursor when done.

What is the use of cursor?

Cursors are used by database programmers to process individual rows returned by database system queries. Cursors enable manipulation of whole result sets at once. In this scenario, a cursor enables the sequential processing of rows in a result set.

How to fetch the next row for a cursor using FETCH?

Let’s look at how to fetch the next row for a cursor using the FETCH statement in MySQL. For example, you could have a cursor defined in MySQL as follows: The command that would be used to fetch the data from this cursor is: This would fetch the first site_id value into the variable called site_ID.

What is the difference between fetchcursor and fetchmany?

cursor.fetchall () fetches all the rows of a query result. It returns all the rows as a list of tuples. An empty list is returned if there is no record to fetch. cursor.fetchmany (size) returns the number of rows specified by size argument.

How to fetch rows from a cursor in Oracle/PLSQL?

After declaring and opening your cursor, the next step is to use the FETCH statement to fetch rows from your cursor. The syntax for the FETCH statement in Oracle/PLSQL is: The name of the cursor that you wish to fetch rows. For example, you could have a cursor defined as: The command that would be used to fetch the data from this cursor is:

What is the use of fetch in SQL?

A fetch statement retrieves rows one at a time from the result set of a multi-row query – in other words it. advances the cursor to the next row. CLOSE a cursor: CLOSE cursor_name; Closing a cursor releases the context area.

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