How to Loop Through SQL Server Records Using Cursors?

Looping Through Records in SQL Server

Looped queries are common for retrieving and processing data from database tables. This guide will demonstrate how to loop through a set of records using T-SQL and cursors in SQL Server.

Creating a Cursor

In order to loop through a set of records, you must first create a cursor. A cursor is a temporary pointer that can be used to iterate through the rows returned by a query. The following code defines a cursor called @MyCursor:

DECLARE @MyCursor CURSOR;

Setting Up the Query

Next, you need to set up the query that will retrieve the data you want to loop through. In your example, you have a query that selects the top 1000 records from a table where StatusID equals 7. You can use this query to populate the cursor:

SET @MyCursor = CURSOR FOR
select top 1000 YourField from dbo.table
where StatusID = 7

Fetching and Processing Records

Once the cursor is created and populated, you can fetch the records row by row into a local variable, such as @MyField:

OPEN @MyCursor
FETCH NEXT FROM @MyCursor INTO @MyField

The FETCH NEXT statement retrieves the next row from the cursor and assigns its value to the specified variable.

Looping Condition

To create a loop, you need a condition that determines when to stop fetching records. In this case, you can use the @@FETCH_STATUS system variable, which returns the status of the cursor:

WHILE @@FETCH_STATUS = 0
BEGIN

As long as the value of @@FETCH_STATUS is 0, the loop will continue to execute. When all records have been fetched, @@FETCH_STATUS will be set to -1 and the loop will terminate.

Processing Logic

Within the loop, you can execute your desired logic on the fetched data. For example, you could print the value of YourField to the console or update a related record in another table.

/*
  YOUR ALGORITHM GOES HERE
*/

Closing the Cursor

After all records have been processed, you should close and deallocate the cursor to free up system resources:

CLOSE @MyCursor;
DEALLOCATE @MyCursor;

By following these steps, you can easily loop through a set of records in SQL Server and perform the necessary operations.

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