There's a data type precedence that it uses to determine which value should be c... | Hacker News

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		valiant55 45 days ago \| parent \| context \| favorite \| on: C# strings silently kill your SQL Server indexes i... There's a data type precedence that it uses to determine which value should be casted[0]. Nvarchar is higher precedence, therefore the varchar value is "lifted" to an nvarchar value first. This wouldn't be an issue if the types were reversed. 0: https://learn.microsoft.com/en-us/sql/t-sql/data-types/data-...

Sankozi 44 days ago [–]

So such issues can appear in more products and more datatypes (int and bigint have same problem).

This is really bad rule for SQL's "equality" operator.

Still optimizer should be able to handle it - if the result is the same, optimizer should take faster path.

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