-- Table: operation_message
CREATE TABLE [operation_message] (
    [message_id] int NOT NULL,
    [operation_id] int NOT NULL,
    [message_text] nvarchar(300) NOT NULL,
    [message_time] datetime NOT NULL DEFAULT (getdate()),
    CONSTRAINT [PK_operation_message] PRIMARY KEY ([message_id], [operation_id])
);
GO

ALTER TABLE [operation_message] ADD FOREIGN KEY ([operation_id]) REFERENCES [operation] ([operation_id]);
GO