SQL Server 2016

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CREATE TABLE [dbo].[CustomerTransaction]
(
    [CustomerTransactionid] [int] identity(1,1) primary key NOT NULL,
    [Customerid] [int] NOT NULL
        DEFAULT TRY_CONVERT(integer, SESSION_CONTEXT(N'CustomerID')),
    [QuantityBought] [int] NULL,
);
CREATE OR ALTER VIEW dbo.CustomerOneTransaction
AS
    SELECT
        CT.CustomerTransactionid,
        CT.Customerid,
        CT.QuantityBought
    FROM dbo.CustomerTransaction AS CT
    WHERE
        CT.Customerid = 1
        AND TRY_CONVERT(integer, SESSION_CONTEXT(N'CustomerID')) = 1
    WITH CHECK OPTION;
-- On connection
EXECUTE sys.sp_set_session_context
    @key = N'CustomerID',
    @value = 1;
INSERT dbo.CustomerOneTransaction (QuantityBought) VALUES (4);
1 rows affected

UPDATE dbo.CustomerOneTransaction SET Customerid = 2;
Msg 550 Level 16 State 1 Line 1
The attempted insert or update failed because the target view either specifies WITH CHECK OPTION or spans a view that specifies WITH CHECK OPTION and one or more rows resulting from the operation did not qualify under the CHECK OPTION constraint.
Msg 3621 Level 0 State 0 Line 1
The statement has been terminated.

DELETE dbo.CustomerOneTransaction;
1 rows affected

-- Setting CustomerID to 2
EXECUTE sys.sp_set_session_context
    @key = N'CustomerID',
    @value = 2;
INSERT dbo.CustomerOneTransaction (QuantityBought) VALUES (4);
Msg 550 Level 16 State 1 Line 1
The attempted insert or update failed because the target view either specifies WITH CHECK OPTION or spans a view that specifies WITH CHECK OPTION and one or more rows resulting from the operation did not qualify under the CHECK OPTION constraint.
Msg 3621 Level 0 State 0 Line 1
The statement has been terminated.