Union and Joins

Sandeep Kumar

10y1k

What is difference between Union and Joins? And where w use this in sql srver?

4 Replies

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Rajeesh Menoth10y ago
Hi,

joins combine data into new columns. If two tables are joined together, then the data from the first table is shown in one set of column alongside the second table’s column in the same row.

Unions combine data into new rows. If two tables are “unioned” together, then the data from the first table is in one set of rows, and the data from the second table in another set. The rows are in the same result.

Reference :

http://www.essentialsql.com/what-is-the-difference-between-a-join-and-a-union/

http://www.allinterview.com/showanswers/13863/what-is-the-difference-between-join-and-union.html
Rajeev Punhani10y ago
Hi Sandeep,

UNION combines the results of two or more queries into a single result set that includes all the rows that belong to all queries in the union.
By using JOINs, you can retrieve data from two or more tables based on logical relationships between the tables. Joins indicate how SQL should use data from one table to select the rows in another table.
If the above solution is helpful then,accept the answer.
Nigel Fernandes10y ago
In simple terms: UNION combines rows from two or more tables JOIN Combines columns from two or more tables
Raja T10y ago
Union:
The UNION operator is used to combine the result-set of two or more SELECT statements.
more details check out below links

http://www.w3schools.com/sql/sql_union.asp

http://www.codeproject.com/Articles/716224/SQL-Server-What-exactly-are-UNION-and-UNION-All

https://www.mssqltips.com/sqlservertip/1387/union-vs-union-all-in-sql-server/

Join :

In SQL joins are used to get data from two or more tables based on relationship between some of the columns in tables

more details check below links

http://www.aspdotnet-suresh.com/2011/12/different-types-of-joins-in-sql-server.html

https://www.mssqltips.com/sqlservertip/1667/sql-server-join-example/

http://www.techonthenet.com/sql_server/joins.php

Differences between JOIN and UNION

1. UNION combines the result set of two or more select queries into a single result set which includes all the rows from all the queries in the UNION, where as JOIN retrieves data from two or more tables based on logical relationships between the tables.

2. In short, UNION combines rows from 2 or more tables, where JOIN combines columns from 2 or more tables.