Microsoft Office Tutorials and References
In Depth Information
Writing Expressions in Access
Table 2-1
Operators in Order of Precedence
Operator
Purpose
Example
Grouping
( )
(2+2)*5 returns 20 .
^
Exponentiation (raising a
number to a specified power)
5^2 returns 25 .
Multiplication, division
* /
5*6/3 returns 10 .
+ –
6+6–2 returns 10 .
&
String concatenation (connect-
ing chunks of text)
“Hello” & “There”
returns HelloThere .
The order or precedence that operators follow can be a real gotcha if you’re
not careful. Take a look at the following simple expression, which includes
an addition operator (+) and a multiplication operator (*):
5+3*2
When you do the math, do you get 16 — or do you get 11? If you do the
addition first (5 + 3 = 8) and then the multiplication (2 * 8), you end up with 16.
But if you do the multiplication first (3 * 2 = 6) and then the addition (6 + 5),
you end up with 11. So which is the correct answer: 11 or 16?
Book III
Chapter 2
Give up? The correct answer (and the one Access comes up with) is 11,
because the order-of-precedence rules state that multiplication and division
are always performed before addition or subtraction.
Multiplication and division are performed in order of precedence. If an
expression involves both of those operations, they’re executed in left-to-
right order. In the following expression, the division operation takes place
first because it’s to the left of the multiplication operation:
10/5*3
The result of the preceding expression is 6, because 10 divided by 5 is 2, and
2 times 3 equals 6.
Addition and subtraction work the same way. If an expression includes both
addition and subtraction, the calculations take place in left-to-right order.
You can control the order of precedence by using parentheses. Access
always works from the innermost parentheses to the outermost, as in the
following example expression:
5^2+((5-1)*3)
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