# SQL Server: Bulk Update with JOIN

> Update many rows from a supplied list of IDs + values using a temp table and JOIN. Ideal for data fixes.

- URL: https://webdevrock.uk/snippets/sql-bulk-update-join/
- Tags: sql, sql-server, data-fix, bulk-update
- Updated: 2026-02-14
- Requires: SQL Server 2008+

## Problem

You have a list of record IDs and their new values and you need to apply them in one safe, repeatable update.

## Solution

Load the updates into a temp table, preview the join, then run an `UPDATE ... FROM` inside a transaction.

```sql
-- 1) Load updates
CREATE TABLE #temp_updates (
  id INT NOT NULL PRIMARY KEY,              -- match target_table.id type
  new_some_column NVARCHAR(255) NOT NULL    -- match target_table.some_column type/length
);

INSERT INTO #temp_updates (id, new_some_column) VALUES
(123, N'Updated Value A'),
(456, N'Updated Value B'),
(789, N'Updated Value C');

-- 2) Preview what will change (always do this first)
SELECT t.id, t.some_column AS old_value, tu.new_some_column AS new_value
FROM target_table t
JOIN #temp_updates tu ON tu.id = t.id;

-- 3) Apply update (transaction makes it easy to rollback if needed)
BEGIN TRAN;

UPDATE t
SET t.some_column = tu.new_some_column
FROM target_table t
JOIN #temp_updates tu ON tu.id = t.id;

SELECT @@ROWCOUNT AS rows_updated;

-- If the rowcount looks wrong, rollback instead of commit.
COMMIT; -- or ROLLBACK;

DROP TABLE #temp_updates;
```

[Build the #temp table from rows pasted from a spreadsheet in List to SQL](https://webdevrock.uk/tools/list-to-sql/)

## Notes

- SQL Server syntax: UPDATE ... FROM and #temp tables are session-scoped.
- Add a PRIMARY KEY on id to prevent duplicate IDs in the update list.
- For large lists, insert in batches and consider indexing the temp table if you join on more than one column.
- If you only want to update changed rows, add: ```WHERE t.some_column <> tu.new_some_column OR t.some_column IS NULL```