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Conversion Precedence in SQL Server

Kenneth Fisher sorts out data types:

With the expectation that you would get back a decimal. Did you wonder why it converted the integers to decimals rather than the other way around? If not you probably should have. I’ll give you a hint. It’s not because it’s the first value in the equation, although that does make a difference.

Thought about it? In case you didn’t figure it out T-SQL (and again, I’m going to say all programing languages where implicit conversions are allowed) has a conversion precedence order. In other words in any calculation where an implicit conversion is required the datatype with a value higher on the list is converted to the datatype with the lower value on the list.

The parenthetical statement above is correct. This makes things really convenient until you have an implicit conversion you weren’t expecting. There’s an advantage to explicit-only languages, though those do involve more typing.

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