SQL WHERE Clause

The SQL WHERE syntax

A WHERE clause with a SELECT statement:

1. SELECT column–names
2. FROM table–name
3. WHERE condition

A WHERE clause with an UPDATE statement:

1. UPDATE table–name
2. SET column–name = value
3. WHERE condition

A WHERE clause with a DELETE statement:

1. DELETE table–name
2. WHERE condition

 

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SQL WHERE Clause Examples

Problem: List the customers in Sweden

1. SELECT Id, FirstName, LastName, City, Country, Phone
2. FROM Customer
3. WHERE Country = ‘Sweden’

Results:  2 records

 

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Problem: Update the city to Sydney for supplier Pavlova, Ltd.

1. UPDATE Supplier
2. SET City = ‘Sydney’
3. WHERE Name = ‘Pavlova, Ltd.’

Results: 1 record updated.

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Problem: Delete all products with unit price higher than $50.

1. DELETE FROM Product
2. WHERE UnitPrice > 50

Results: 7 records deleted.
Note: Referential integrity may prevent this deletion.
A better approach may be to discontinue the product, that is, set IsDiscontinued to true.