What is fetch status?

What is fetch status?

@@FETCH_STATUS is a system function that returns the status of the last FETCH statement issued against any opened cursor.

What is fetch status in SQL Server?

@@Fetch_Status: We can say that the @@Fetch_Status function returns the status of a recent fetch operation of a cursor. It is used with a while loop. The @@fetch_status returns 0,-1 or -2. When it returns 0 the fetch operation was successful.

What is cursor in PostgreSQL?

A PL/pgSQL cursor allows you to encapsulate a query and process each individual row at a time. Typically, you use cursors when you want to divide a large result set into parts and process each part individually. If you process it at once, you may have a memory overflow error.

How does Postgres cursor work?

When CURSOR is declared with a select statement, DB will execute the select statement and then have the result stored in DB memory. When FETCH is called on the CURSOR , DB will just read the result moving on the CURSOR . When the CURSOR is closed, results stored is removed from memory.

How is the fetch clause used in PostgreSQL?

However, the FETCH clause, which has been available in PostgreSQL since 2008, can also be used to retrieve a subset of rows from a table. The difference between LIMIT and FETCH is that FETCH makes use of a cursor, which allows you to read through a result set a few rows at a time.

When to return the fetch status in SQL?

This FETCH status is returned if a row that should be returned in the FETCH statement is deleted in case that we used the KEYSET option while declaring the cursor (note that KEYSET option specifies that the membership and order of the rows in the cursor are fixed when the cursor is opened).

Where does the cursor go after a fetch in PostgreSQL?

After fetching some rows, the cursor is positioned on the row most recently retrieved. If FETCH runs off the end of the available rows then the cursor is left positioned after the last row, or before the first row if fetching backward.

What is the status of the FETCH statement?

This function returns the status of the last cursor FETCH statement issued against any cursor currently opened by the connection. The FETCH statement was successful. The FETCH statement failed or the row was beyond the result set. The row fetched is missing. The cursor is not performing a fetch operation.