复制CREATE TABLE t1 (a int NULL,隐性
b int NOT NULL DEFAULT 99) GO CREATE TRIGGER t1trig ON t1 FOR INSERT, UPDATE AS IF UPDATE(a) AND UPDATE(b) PRINT FIRING GO --When two values are inserted, the UPDATE is TRUE for both columns and the trigger is activated. INSERT t1 (a, b) VALUES (1, 2) --When two values are updated, the UPDATE is TRUE for both columns and the trigger is activated. UPDATE t1 SET a = 1, b = 2 --When an explicit NULL is inserted in column a, the UPDATE is TRUE for both columns and the trigger is activated. INSERT t1 VALUES (NULL, 2) --When an explicit NULL is updated in column a, the UPDATE is TRUE for both columns,the trigger is activated. UPDATE t1 SET a = NULL, b = 2 --When an implicit NULL is inserted in column a, the UPDATE is TRUE for both columns and the trigger is activated. INSERT t1 (b) VALUES (2) --When column a is updated with an implicit NULL, the UPDATE is FALSE for both columns and the trigger is not activated. UPDATE t1 SET b = 2 --When the default value is implicitly inserted in column b, the UPDATE is TRUE for both columns and the trigger is activated. INSERT t1 (a) VALUES (2) --When column b is updated with an implicit NULL, the UPDATE is FALSE for both columns and the trigger is not activated. UPDATE t1 SET a = 2 --When the default value is explicitly inserted in column b, the UPDATE is TRUE for both columns and the trigger is activated. INSERT t1 (a, b) VALUES (2, DEFAULT) --When column b is updated explicitly with the default value, the UPDATE is TRUE for both columns and the trigger is activated. UPDATE t1 SET a = 2, b = DEFAULT 1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.23.24.25.26.27.28.29.30.31.32.33.34.35.36.37.38.39.40.41.42.43.44.45.46.47.48.49.50.51.52.53.54.55.56.57.58.59.60.61.
