inner join and outer join code example

Example 1: joins in sql

INNER JOIN:
is used when retrieving data from multiple
tables and will return only matching data.

LEFT OUTER JOIN:
is used when retrieving data from
multiple tables and will return
left table and any matching right table records.

RIGHT OUTER JOIN:
is used when retrieving data from
multiple tables and will return right
table and any matching left table records

FULL OUTER JOIN:
is used when retrieving data from
multiple tables and will return both
table records, matching and non-matching.



INNER JOIN :
SELECT select_list From TableA A
Inner Join TableB B
On A.Key = B.Key


LEFT OUTER JOIN :
SELECT select_list From TableA A
Left Join TableB B
On A.Key = B.Key

(where b.key is null)//For delete matching data



RIGTH OUTER JOIN :
SELECT select_list From TableA A
Right Join TableB B
On A.Key = B.Key


FULL JOIN :
SELECT select_list From TableA A
FULL OUTER Join TableB B
On A.Key = B.Key

Example 2: inner join

INNER JOIN is used when retrieving data from
multiple tables and will return only matching data.

example=
Select P.FIRST_NAME , M.DRUG_ID
FROM PATIENTS P
INNER JOIN MEDICATIONS M ON P.PATIENTS_ID = M.PATIENTS_ID

Example 3: inner join vs outer join

INNER JOIN:
is used when retrieving data from multiple
tables and will return only matching data.


FULL OUTER JOIN:
is used when retrieving data from
multiple tables and will return both
table records, matching and non-matching.