Thread: How to compare two tables

I have two tables able A and table B. whats the query to compare two tables.

What you want to compare data or metadata ?

What tables want to compare data give correct table names ?

To compare two tables or to join two tables, we need to go for joins or sub-query concept.

SELECT * FROM t1 WHERE NOT EXISTS (SELECT * FROM t2 WHERE t2.Id = t1.Id)

or

SELECT * FROM t1 LEFT OUTER JOIN T2 on t1.Id = t2.Id WHERE t2.Id IS NULL

or

SELECT Id, Col1 FROM t1 EXCEPT SELECT Id, Col1 FROM t2

SELECT * FROM (SELECT Id, Col1 FROM t1, 'old'
UNION ALL
SELECT Id, Col1 FROM t2, 'new') t
ORDER BY Id

hi don't know what he want to say,
for comparing of two tables as i understood u can do perform the join operation with the basis of two column which must be number type can easily and perfect comprise, except this you can perform minus operation to perform which is matching or not u also get same thing by union operator. hope u understand.

Using SET OPERATORS(UNION,UNION ALL,INTERSECT,MINUS)

Select * from table1
MINUS
Select * from table2

what we have to compare between two table.i am confused .

comparing two tables , could be in two way.
1. table structure
2. table data

table structure doesn't seems to realistic example as two tables can have different attributes but still can be done by calling user_objects/dba_objects or dynamic views "v$" of database.

table data comparison is easy as many of my friends already suggested you with multiple ways. So it can be done in either of those.

UNION,UNION ALL,INTERSECT,MINUS USING IT WE CAN COMPARE TWO TABLES