Sql server® 2012 t-sql fundamentals

1. 

( ) (Parentheses)

2. 

* (Multiplication), / (Division), % (Modulo)

3. 

+ (Positive), – (Negative), + (Addition), + (Concatenation), – (Subtraction)

4. 

=, >, <, >=, <=, <>, !=, !>, !< (Comparison operators)

5. 

NOT

6. 

AND

7. 

BETWEEN, IN, LIKE, OR

8. 

= (Assignment)

For example, in the following query, AND has precedence over OR.

SELECT orderid, custid, empid, orderdate 

FROM Sales.Orders 

WHERE 

        custid = 1 

    AND empid IN(1, 3, 5) 

    OR  custid = 85 

    AND empid IN(2, 4, 6);

The query returns orders that were either “placed by customer 1 and handled by employees 1, 3, 

or 5” or “placed by customer 85 and handled by employees 2, 4, or 6.” 

Parentheses have the highest precedence, so they give you full control. For the sake of other people 

who need to review or maintain your code and for readability purposes, it’s a good practice to use 

parentheses even when they are not required. The same is true for indentation. For example, the fol-

lowing query is the logical equivalent of the previous query, only its logic is much clearer. 

SELECT orderid, custid, empid, orderdate 

FROM Sales.Orders 

WHERE 

      (custid = 1 

        AND empid IN(1, 3, 5)) 

    OR 

      (custid = 85 

        AND empid IN(2, 4, 6));

www.it-ebooks.info

---