sql join with where code example

Example 1: 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 2: use where instead of join

# using WHERE ANSI-89 syntax
SELECT *
  FROM TABLE_A a,
       TABLE_B b
 WHERE a.id = b.id

# using JOIN ANSI-92 syntax
 SELECT *
  FROM TABLE_A a
  JOIN TABLE_B b ON b.id = a.id