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union and union all

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Delightful Dolphin answered on January 7, 2021 Popularity 10/10 Helpfulness 1/10

answer union and union all

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union and union all

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-2

select null
union all
select null

Popularity 10/10 Helpfulness 1/10 Language sql

Source: stackoverflow.com

Tags: sql union union-all

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Contributed on Mar 16 2022

Delightful Dolphin

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what is the difference between union and union all

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UNION ALL:
COMBINES THE RESULT OF 2 QUERY AND
DOESN'T REMOVE DUPLICATE ROWS
AND DOESN'T SORT BY FIRST COLUMN

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

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Tags: between

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Contributed on Jan 07 2021

Obedient Ocelot

0 Answers Avg Quality 2/10

union vs union all in sql

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UNION ALL:
COMBINES THE RESULT OF 2 QUERY AND
DOESN'T REMOVE DUPLICATE ROWS
AND DOESN'T SORT BY FIRST COLUMN

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

Popularity 10/10 Helpfulness 3/10 Language sql

Source: Grepper

Tags: sql

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Contributed on Jan 28 2021

Obedient Ocelot

0 Answers Avg Quality 2/10

union and union all difference

Comment

-1

UNION
The UNION command is used to select related information from two tables,
which is like a JOIN command. However, when using UNION command, all the 
selected columns need to be of the same data type. With UNION, only distinct 
values are selected.
 
UNION ALL
UNION ALL command is equal to UNION command, except that UNION ALL selects all 
the values.
 
The difference between Union and Union all is that Union all will not eliminate
duplicate rows, instead it just pulls all the rows from all the tables fitting 
your query specifics and combines them into a table.
 
A UNION statement effectively does a SELECT DISTINCT on the results set. 
If you know that all the records returned are unique from your union, 
use UNION ALL instead, it gives faster results.

SELECT column1, Column2 ...Column (N) FROM tableA
UNION
SELECT column1, Column2 ...Column (N) FROM tableB;

SELECT column1, Column2 ...Column (N) FROM tableA
UNION ALL
SELECT column1, Column2 ...Column (N) FROM tableB;

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Source: Grepper

Tags: difference d

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Contributed on Jun 14 2022

Rasel Ahmed

0 Answers Avg Quality 2/10

union and union all

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