これは、EXISTS
よりも大幅に高速です 方法:
SELECT [EmailAddress], [CustomerName] FROM [Customers] WHERE [EmailAddress] IN
(SELECT [EmailAddress] FROM [Customers] GROUP BY [EmailAddress] HAVING COUNT(*) > 1)
これは、EXISTS
よりも大幅に高速です 方法:
SELECT [EmailAddress], [CustomerName] FROM [Customers] WHERE [EmailAddress] IN
(SELECT [EmailAddress] FROM [Customers] GROUP BY [EmailAddress] HAVING COUNT(*) > 1)