Select Col01, Col02 From TableName Where @CustomerLastNameLowerCaseVariable = LOWER (CustomerLastName)
Select Col01, Col02 From TableName Where LOWER (CustomerLastName) = @CustomerLastNameLowerCaseVariable
On the face of it, there does not seem to be much of a difference. The execution plan says "Go for either one".
My question is more on the best practices side of things. As queries grow more complex which one of these is the better practice?