select two tables sql code example

Example 1: how to select from two tables in sql

-- With JOIN
-- No row if id does not exist in t2
SELECT t1.name, t2.salary FROM t1 JOIN t2 on t1.id = t2.id;
SELECT t1.*, t2.salary FROM t1 JOIN t2 on t1.id = t2.id;
-- A row with a NULL salary is returned if id does not exist in t2
SELECT t1.name, t2.salary FROM t1 LEFT OUTER JOIN t2 on t1.id = t2.id;

-- With UNION: distinct values
SELECT emp_name AS name from employees
UNION
SELECT cust_name AS name from customers;

-- With UNION ALL: keeps duplicates (faster)
SELECT emp_name AS name from employees
UNION ALL
SELECT cust_name AS name from customers;

Example 2: how to join tables in sql

JOINING 2 Tables in sql

SELECT X.Column_Name , Y.Column_Name2
FROM TABLES1_NAME X 
INNER JOIN TABLES2_NAME Y ON X.Primary_key = Y.Foreign_key;


--FOR EXAMPLE
--GET THE FIRST_NAME AND JOB_TITLE
--USE EMPLOYEES AND JOBS TABLE
--THE RELATIONSHIP IS JOB_ID

SELECT E.FIRST_NAME , J.JOB_TITLE
FROM EMPLOYEES E
INNER JOIN JOBS J ON J.JOB_ID = E.JOB_ID;