how to insert into multiple tables

Inserts are done on single tables, what you can do is start a Transaction and insert into the two tables via two queries and Commit when done.

This will make sure the two queries are done in an atomic fashion.

I found it over here

IMO the best way to do this is to create a parameterized stored procedure to do the inserts, see: CREATE PROCEDURE [^]. Then execute the procedure using SqlCommand.ExecuteNonQuery Method [^]

And as pointed out, use transactions properly, see both BEGIN TRANSACTION [^] and SqlTransaction Class[^]

To be honest, you can actually execute multiple statements with a single call from C#. This is done by executing a batch, but I don't suggest this approach for several reasons:
- probably a maintenance nightmare
- logic is hard to follow
- no good reusing of code etc etc.

If you need to do this via front end then just use join in your sql.

Let's see the code,

SELECT * FROM CustomerTable c 
LEFT JOIN AddressTable a ON a.CustomerId = c.CustomerId
WHERE c.CustomerId = @CustomerId

set @CustomerId to your customer id. You will definitely get your result.

use storedprocedure to achive this as

CREATE PROCEDURE [dbo].[Insert_Answer] 
	
AS
DECLARE  @LocalError int,
        
         BEGIN TRANSACTION
    
	insert query 1
         insert query 2
         insert query 3
	
       SELECT @LocalError = @@Error
     IF NOT @LocalError = 0
      BEGIN
        ROLLBACK TRANSACTION
    SELECT  Error = @LocalError
        
        END
ELSE
        BEGIN
     COMMIT TRAN
   
    SELECT  Error = 0 
    END

HI TRY THIS WAY,

CREATE TABLE CUSTOMERtable(firstname VARCHAR(100),surname VARCHAR(100),phone VARCHAR(100));
CREATE TABLE ADDRESStable (address VARCHAR(100), country VARCHAR(100), town VARCHAR(100))

CREATE proc InserttABLE
(
@firstname VARCHAR(100),
@surname VARCHAR(100),
@phone VARCHAR(100),
@address VARCHAR(100),
@country VARCHAR(100),
@town VARCHAR(100)
)
as
BEGIN
  INSERT INTO @TABLE VALUES(@firstname,@surname,@phone,@address,@country,@town);
INSERT INTO  CUSTOMERtable VALUES(@firstname,@surname,@phone)
 INSERT INTO ADDRESStable VALUES(@address,@country,@town);
 END