CREATE TRIGGER dbo.TrgUpnInsert
  ON [CNLH Security Authentication].dbo.DateTimestamp
    AFTER INSERT,
    INSERT INTO [CNLH Security Authentication].dbo.EntranceInformation (DateTimestamp) Values (CURRENT_TIMESTAMP);

CREATE TRIGGER ModDate
    ON TableX
    AFTER INSERT
AS
BEGIN
    UPDATE X
    SET ModifiedDate = CURRENT_TIMESTAMP
    FROM TableX X
    JOIN inserted i ON X.key = i.key -- change to whatever key identifies
                                     -- the tuples
END

ALTER TABLE myTable
  ADD CONSTRAINT CONSTRAINT_NAME
    DEFAULT CURRENT_TIMESTAMP FOR myColumn

IF OBJECT_ID('tempdb..#temp') IS NOT NULL
    DROP TABLE #temp

CREATE TABLE #temp (
    col1 VARCHAR(10)
    ,col2 DATETIME
    )

ALTER TABLE #temp ADD CONSTRAINT ConstraintForTemp DEFAULT CURRENT_TIMESTAMP
FOR col2

INSERT INTO #temp (col1)
VALUES ('abc')

SELECT *
FROM #temp