Sqlsever the difference between the base Union and union all, that is, whether the duplicates are all displayed

Town Field Poem:
——— Dream who feel, the water month Build blog. Baiqian tribulation, only know the vicissitudes of the world.
——— today holds the Buddhist language, the technology is boundless willing to learn. Willing to do what you learn, cast a conscience blog.
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1 Base Code

1  UseMaster2 Drop DatabaseHelloWorld3 4 5 --Create a database6 Create DatabaseHelloWorld7 8 9 Ten --use helloworld1 this database One  UseHelloWorld A  - --Create a table Fojiateacher - Create TableFojiateacher the ( -Idint Primary Key Identity(1,1),    -Namenvarchar(Ten), -Classnchar(2), +Scorefloat - ) +  A --Create a table Fojiateacher at Create TableDaojiateacher - ( -Idint Primary Key Identity(1,1),    -Namenvarchar(Ten), -Classnchar(2), -Scorefloat in ) -  to  + Select *  fromFojiateacher - Select *  fromDaojiateacher the  * --insert these lines of content into this teacher, which I insert once, simply modify, and insert again $ Insert  intoFojiateacherPanax Notoginseng        Values('burning lamp Ancient Buddha','Buddhist', -), -('Buddha Buddha','Buddhist', -), the('Maitreya Buddha','Buddhist', -), +('Buddha Buddha','Buddhist', -), A('Buddhist Bodhisattva','Buddhist', -), the('The Buddha','Buddhist',101)--For convenience, add 1 points to the Bodhisattva +  - Insert  intoDaojiateacher $        Values('nu wa Niang','Taoism', -), $('Yangmn greedy wolf too star June','Taoism',101), -('Yin Jing giant door Yuan Xing June','Taoism',101), -('Live Lu, the true star','Taoism',101), the('Xuan Ming Wen qu new star June','Taoism',101) - Wuyi  the Select *  fromDaojiateacher - Select *  fromFojiateacher

2 table1

3 Table 2

4 Key Code1

1 -- Buddha Road A home, Socre for 100 has, show its ID 2 3 -- Union has duplicate content in one column, showing only 1 4 Select  from where score=5Union6Select  fromwhere score=

5 Show Key Code1

6 Key Code2

1 -- UNION ALL has duplicate content in one column, all displayed 2 Select  from where score=3Unionall4Select  from where score=

7 Show Key Code2

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The essence of the blog, in the technical part, more in the town yard a poem.
Sqlsever is a good language, worth studying hard. Familiar with the database of additions and deletions, write procedures necessary.
If the content of the post can be improved, or even the wrong place, please leave a comment, I will try to correct, strive to cast a conscience blog.
Note: This article is only as a scientific research study, if I inadvertently violated your rights and interests, please be sure to timely inform, I will make corrections.

Sqlsever the difference between the base Union and union all, that is, whether the duplicates are all displayed