JOINS ACTUALY PERFORMS TWO OR MORE TABLES COMBINED INTO A SINGLE RESULT SET.
THERE ARE FOUR TYPES OF JOINS AVAILALBE IN SQLSERVER
1) INNER JOIN
2) OUTER JOIN(LEFT OUTER JOIN,RIGHT OUTER JOIN)
3) FULL JOIN
4) CROSS JOIN
5) SELF JOIN
EXAMPLES:
INNSER JOIN:
SELECT * FROM EMPDETAILS INNER JOIN EMPSALARY ON EMPDETAILS.EMPID=EMPSALARY.EMPID
OUTER JOIN :
LEFT OUTER JOIN:
SELECT * FROM EMPDETAILS LEFT OUTER JOIN EMPSALARY ON EMPDETAILS.EMPID=EMPSALARY.EMPID
RIGHT OUTER JOIN:
SELECT * FROM EMPDETAILS RIGHT OUTER JOIN EMPSALARY ON EMPDETAILS.EMPID=EMPSALARY.EMPID
CROSS JOIN:
SELECT * FROM EMPDETAILS CROSS JOIN EMPSALARY
SELF JOIN:
SELECT EMPID A ,EMPNAME B FROM EMPDETAILS A ,EMPSALARY B
WHERE A.EMPID=B.EMPID