A strange operation problem in SQL Server: -100/-100*10 = 0

Question

• If you execute SELECT -100/-100*10 the result is 0.
• If you execute SELECT (-100/-100)*10 the result is 10.
• If you execute SELECT -100/(-100*10) the result is 0.
• If you execute SELECT 100/100*10 the result is 10.

BOL states:

When two operators in an expression have the same operator precedence level, they are evaluated left to right based on their position in the expression.

And

Level   Operators
  1     ~ (Bitwise NOT)
  2     * (Multiplication), / (Division), % (Modulus)
  3     + (Positive), - (Negative), + (Addition), + (Concatenation), - (Subtraction), & (Bitwise AND), ^ (Bitwise Exclusive OR), | (Bitwise OR)

Is BOL wrong, or am I missing something? It seems the - is throwing the (expected) precedence off.

Answer 1

According to the precedence table, this is the expected behavior. The operator with higher precedence (/ and *) is evaluated before operator with lower precedence (unary -). So this:

-100 / -100 * 10

is evaluated as:

-(100 / -(100 * 10))

Note that this behavior is different from most programming languages where unary negation has higher precedence than multiplication and division e.g. VB, JavaScript.