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How to Compare Two Queries in SQL

Last Updated : 08 Jun, 2021
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Queries in SQL :
A query will either be an invitation for data results from your info or for action on the info, or each. a question will provide you with a solution to a straightforward question, perform calculations, mix data from totally different tables, add, change, or delete data from info.

Creating a Database :
We use CREATE DATABASE command to create a new SQL database.

Syntax –

CREATE DATABASE db_name;

Creating a Table into a created Database :
We use the CREATE TABLE command to create a new SQL database.

Syntax  –

CREATE TABLE table_name (
   col1 datatype,
   col2 datatype, 
   col3 datatype,
 );

Inserting the values into created Table :
We use INSERT INTO command to create a new SQL database.

Syntax –

INSERT INTO table_name
VALUES (value1, value2, value3);

Example Code to create a database and a table into it –

PHP




CREATE DATABASE myDatabase;
  
CREATE TABLE myTable
(
Pid int,
FName varchar(255),
LName varchar(255),
Adrs varchar(255),
District varchar(255)
);
  
INSERT INTO myTable (Pid, FName, LName, Adrs, District)
VALUES ('1','Krishna','Kripa','Jansa','Varanasi');


Output –

myDatabase: myTable

Pid

FName

LName

Adrs

District

1

Krishna

Kripa

Jansa

Varanasi

Comparison of Queries :
For example, we’ve 2 similar tables in completely different databases and we wish to understand what’s different. Here are the scripts that make sample databases, tables, and information.

PHP




CREATE DATABASE myDatabase1;
GO
USE myDatabase1;
GO
  
CREATE TABLE myTable
(
Aid int,
Atype varchar(10),
Acost varchar(10)
);
  
GO
  
INSERT INTO myTable (Aid, Atype, Acost)
  VALUES ('001', '1', '40'),
  ('002', '2', '80'),
  ('003', '3', '120')
GO
  
CREATE DATABASE myDatabase2;
GO
USE myDatabase2;
GO
  
CREATE TABLE myTable
(
Aid int,
Atype varchar(10),
Acost varchar(10)
);
  
GO
  
INSERT INTO myTable (Aid, Atype, Acost)
  VALUES ('001', '1', '40'),
  ('002', '2', '80'),
  ('003', '3', '120'),
  ('004', '4', '160')
  
GO


Output –
For myDatabse1 –

Aid

Atype

Acost

001

1

40

002

2

80

003

3

120

For myDatabase2 –

Aid

Atype

Acost

001

1

40

002

2

80

003

3

120

004

4

160

Compare SQL Queries in Tables by using the EXCEPT keyword :
EXCEPT shows the distinction between 2 tables. it’s wont to compare the variations between 2 tables.

Now run this query where we use the EXCEPT keyword over DB2 from DB1 –

PHP




SELECT * FROM myDatabase2.myTable
EXCEPT
SELECT * FROM myDatabase1.myTable


Output –

Aid

Atype

Acost

004

4

160



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