TSQL Tutorial : Updating Data

Most people eventually want to change the data they've loaded into a database.

The SQL UPDATE command is the means by which this happens. Here's an example:

UPDATE customers

SET Zip='86753-0900'

WHERE City='Reo'

Depending on the data, the WHERE clause in this query might limit the UPDATE to a single row or to many

rows.

You can update all the rows in a table by omitting the WHERE clause:

UPDATE customers

SET State='CA'

You can also update a column using columns in the same table, including the column itself, like so:

UPDATE orders

SET Amount=Amount+(Amount*.07)

Transact-SQL provides a nice extension, the SQL UPDATE command, that allows you to update the values

In one table with those from another. Here's an example:

UPDATE o

SET Amount=Price

FROM orders o JOIN items i ON (o.ItemNumber=i.ItemNumber)

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