question

Hi @MohdOmarDaraz-1660,

Welcome to Microsoft Q&A!

For this type of problem we recommend that you post CREATE TABLE statements for your tables together with INSERT statements with sample data, enough to illustrate all angles of the problem. We also need to see the expected result of the sample.

I suppose that id will never updated in table1 and table2, you could refer below query and check whether it is working:

 update a
 set a.city=b.city,a.name=b.name
 from table3 a  
 inner join 
 (select * from table1
 union
 select * from table2
 except
 select * from table3) b on a.id=b.id

Best regards
Melissa

---

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Dear Melissa,

Thanks for your reply for better understanding

I have table 1 with column name- ID, name, City
value (1,'a','newyork')
value (2,'b','washington')
value (3,'c','dallas')
I have table 2 with column name- ID, name, City
value (10,'x','sydney')
value (20,'y','melbourne')
value (30,'z','queensland')

I did UNION ALL to both of these two table and put data to
table 3 with column name- ID, name, City
and value came
value (1,'a','newyork')
value (2,'b','washington')
value (3,'c','dallas')
value (10,'x','sydney')
value (20,'y','melbourne')
value (30,'z','queensland')

Now I update data to table 1 with column name- ID, name, City
value (555,'qqq','japan')
value (666,'www','china')

also I update data to table 2 with column name- ID, name, City
value (888,'ppp','london')
value (999,'ooo','france')

Now i want to see in table 3

            value (1,'a','newyork')
            value (2,'b','washington')
            value (3,'c','dallas')
            value (10,'x','sydney')
            value (20,'y','melbourne')
            value (30,'z','queensland')
            value (555,'qqq','japan')
            value (666,'www','china')
            value (888,'ppp','london')
            value (999,'ooo','france')

I hope this is not much more understandable and cleared

regards,

Hi @MohdOmarDaraz-1660,

Please refer below:

 insert into  table3
 select * from table1
 union
 select * from table2
 except
 select * from table3

Best regards
Melissa

---

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 insert into  table3
 select * from (
 (select * from table1
 except
 select * from table3) 
 union
 (select * from table2
 except
 select * from table3 ))a

Hi @MohdOmarDaraz-1660,

EXCEPT returns distinct rows from the left input query that aren't output by the right input query.

select from table1
union
select from table2
except
select * from table3

So above whole part is combine all data from table 1 and table 2 and minus all the data from table3 in order to find out all updated part only.

For example, suppose (select from table1 union select from table2) as A and (select * from table3) as B. Then above query is A minus B which are the only updated data.

It is not load full data from table 1 and table 2 to table3 as you mentioned.

Please also refer my complete statement from below:

 drop table if exists Table1,Table2,Table3
    
 create table Table1
 (
 id int,
 name varchar(20),
 city varchar(20)
 )
    
 insert into Table1 values
 (1,'a','newyork'),
  (2,'b','washington'),
 (3,'c','dallas')
    
 create table Table2
 (
 id int,
 name varchar(20),
 city varchar(20)
 )
    
 insert into Table2 values
 (10,'x','sydney'),
 (20,'y','melbourne'),
 (30,'z','queensland')
    
 create table Table3
 (
 id int,
 name varchar(20),
 city varchar(20)
 )
    
 insert into table3
 select *
 from
 ( select * from dbo.table1
 union all
 select * from dbo.table2)t
    
 insert into Table1 values
  (555,'qqq','japan'),
  (666,'www','china')
    
  insert into Table2 values
 (888,'ppp','london'),
 (999,'ooo','france')
    
 --Method 1
 insert into table3
 select * from (
 (select * from table1
 union
 select * from table2)
 except
 select * from table3)a
    
 --Method 2
  insert into  table3
  select * from (
  (select * from table1
  except
  select * from table3) 
  union
  (select * from table2
  except
  select * from table3 ))a
    
  --Method 3
   insert into  table3
  select * from table1
  union
  select * from table2
  except
  select * from table3
    
 select * from table3

Output:

 id name city
 1 a newyork
 2 b washington
 3 c dallas
 10 x sydney
 20 y melbourne
 30 z queensland
 555 qqq japan
 666 www china
 888 ppp london
 999 ooo france

Best regards
Melissa

---

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I guess the column Id in those three tables is unique. If that is a case, I think there should be an index on that column in the tables. If the operation is only to insert data to Table 3 from both Table 1 and 2, you do not need a UNION ALL.

 INSERT INTO Table3
 SELECT * FROM  Table1 WHERE Id NOT IN (SELECT Id FROM Table3);
    
 INSERT INTO Table3
 SELECT * FROM  Table2 WHERE Id NOT IN (SELECT Id FROM Table3);

Hi @MohdOmarDaraz-1660,

According to your requirement, you could consider to create triggers which could insert new data from table1, table2 to table3 antomatically.

Please refer below examples:

 --create triggers on both tables
 CREATE TRIGGER Table1Insert ON table1
 FOR INSERT
 AS
  INSERT INTO table3
  select * FROM inserted
    
  CREATE TRIGGER Table2Insert ON table2
 FOR INSERT
 AS
  INSERT INTO table3
  select * FROM inserted

 --insert some new data in table1 and table2
 insert into Table1 values
   (555,'qqq','japan'),
   (666,'www','china')
        
   insert into Table2 values
  (888,'ppp','london'),
  (999,'ooo','france')

 --query table3
  select * from table3

Output:

 id    name    city
 1    a    newyork
 2    b    washington
 3    c    dallas
 10    x    sydney
 20    y    melbourne
 30    z    queensland
 666    www    china
 555    qqq    japan
 999    ooo    france
 888    ppp    london

Best regards
Melissa

---

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