SQL

SQL UNION ALL Operator

SELECT age
FROM Teachers
UNION ALL
SELECT age
FROM Students;

sql union

-- UNION: distinct values (slower)
SELECT emp_name AS name from employees
UNION       
SELECT cust_name AS name from customers;

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

SQL UNION Operator

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

sql union

Combines the results from 2 or more SELECT statements and returns only
distinct values.
Example: Returns the cities from the events and subscribers tables.
SELECT city FROM events
UNION
SELECT city from subscribers;

union SQL

SQL> SELECT  ID, NAME, AMOUNT, DATE
   FROM CUSTOMERS
   LEFT JOIN ORDERS
   ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
UNION
   SELECT  ID, NAME, AMOUNT, DATE
   FROM CUSTOMERS
   RIGHT JOIN ORDERS
   ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID;

UNION in SQL

#Syntax to execute UNION in SQL

SELECT columnName(s) FROM table1
UNION
SELECT columnName(s) FROM table2;

SQL UNION

SELECT age
FROM Teachers
UNION
SELECT age
FROM Students;

sql union

SELECT
A.ID, SUM(A.COUNTS) AS COUNT_TOTAL
FROM
(
SELECT X AS ID, COUNT(*) AS COUNTS FROM TABLE1 GROUP BY X
UNION ALL
SELECT Y AS ID, COUNT(*) AS COUNTS FROM TABLE1 GROUP BY Y
) A
GROUP BY A.ID
ORDER BY A.ID;

what is union in sql

UNION:
COMBINES THE RESULT OF 2 QUERY AND
REMOVES DUPLICATE ROWS AND
SORTS BY FIRST COLUMN