It is the WHERE clause that determines how many records will be updated.
The following SQL statement will update the ContactName to "Juan" for all records where country is "Mexico":
Example
UPDATE Customers
SET ContactName='Juan'
WHERE Country='Mexico';
SET ContactName='Juan'
WHERE Country='Mexico';
The selection from the "Customers" table will now look like this:
| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
|---|---|---|---|---|---|---|
| 1 |
Alfreds Futterkiste | Alfred Schmidt | Obere Str. 57 | Frankfurt | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Juan | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
| 3 | Antonio Moreno Taquería | Juan | Mataderos 2312 | México D.F. | 05023 | Mexico |
| 4 |
Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
| 5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |
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