How do you implement a FOR EACH loop in SQL Server?

In SQL Server, there’s no direct FOR EACH loop like in other programming languages. Instead, you can use cursors or WHILE loops to achieve the same functionality. Here’s how they work:

Using a Cursor:

1. A cursor allows you to process each row of a result set one at a time.
2. You define a cursor, fetch each row, perform actions, and then move to the next row.
3. Cursors are useful for row-by-row processing but can be slower for large datasets.

Using a WHILE Loop:

1. If you avoid cursors, you can use a temporary table or another structure.
2. A WHILE loop is used to iterate through rows by tracking an index or a counter.
3. This method can be more efficient than using a cursor.

Key Takeaways:

• Cursors are straightforward for row-by-row processing but may impact performance.
• WHILE loops with temporary tables offer an alternative for iterating through data.

For better performance, avoid looping entirely if you can achieve the result using set-based SQL operations, which process all rows at once. This approach is faster and more efficient.