• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

Operators

In the previous section, you were introduced to the use of the & operator. Operators are used in programming languages to aid in the evaluation of expressions. The following table lists operators that you should be familiar with:

*The multiplication operator is used when multiplying fields or values.
/The divide operator is used when dividing fields or values.
The minus operator is used when subtracting fields or values.
>The greater-than operator is used in WHERE clauses to determine whether a first value is greater than the second, such as
SELECT *
FROM Customers 
WHERE CustomerID > 10

The result would return all the CustomerIDs after 10.
<The less-than operator is used in WHERE clauses to determine whether a first value is less than the second, such as
SELECT *
FROM Customers
WHERE CustomerID < 10

The result would return CustomerIDs 1–9.
>=The greater than or equal to operator is used in WHERE clauses to determine whether a first value is greater than or equal to the second, such as
SELECT *
FROM Customers
WHERE CustomerID >= 10

The result would return CustomerIDs of 10 and greater.
<=The less than or equal to operator is used in WHERE clauses to determine whether a first value is less than or equal to the second, such as
SELECT *
FROM Customers
WHERE CustomerID <= 10

The result would return all the CustomerIDs between 1 and 10.
<>, !=Used to check whether a value is not equal to a second.
ANDUsed with the WHERE clause in the SELECT statement. The AND operator returns a second value, such as
SELECT *
FROM Customers
WHERE CustomerID = 1 AND CustomerID = 2

ORUsed with the WHERE clause in the SELECT statement. The OR operator can be used when a certain condition needs to be met or when you can settle for a second, such as
SELECT *
FROM Customers
WHERE CustomerID = 1 OR CustomerID > 2

LIKEThe LIKE operator is used with WHERE clauses when a wildcard needs to be performed, such as
SELECT *
FROM Customers
WHERE LastName LIKE 'Smi%'

which would return all customers whose last names start with “Smi.”
NOTTypically used in conjunction with the LIKE operator, the NOT operator is used when a value is not going to be LIKE the value of a second, such as
SELECT *
FROM Customers
WHERE LastName NOT LIKE 'Smi%'

_The underscore operator is used with WHERE clauses and is performed when you do not know the second value, such as
SELECT *
FROM Customers
WHERE BillingState LIKE 'A_'

which would return all customers' states that begin with A, such as AK, AL, AR, and AZ.
%The multiple character operator is similar to the underscore operator except that it allows for multiple characters, whereas the underscore operator allows for only two.



PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint