\u4eca\u5929\u5728\u5199\u89e6\u53d1\u5668\u7684\u65f6\u5019\u7a81\u7136\u60f3\u5230\u8fd9\u4e00\u70b9\uff0c\u4e3a\u4e86\u9a8c\u8bc1\u60f3\u6cd5\uff0c\u505a\u4e86\u4e00\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u3002
\n\u5982\u679c\u4e00\u4e2a\u5b57\u6bb5\u62e5\u6709\u9ed8\u8ba4\u503c\uff0c\u4e14\u5305\u542b\u4e00\u4e2aBEFORE\u7684\u884c\u7ea7\u89e6\u53d1\u5668\uff0c\u5f53\u4e0d\u6307\u5b9a\u503c\u65f6\uff0c\u4e8c\u8005\u7684\u751f\u6548\u987a\u5e8f\u5982\u4f55\uff1a<\/p>\n
SQL> create table t_trigger_default (id number, col varchar2(30) default 'default');\r\nTable created.\r\nSQL> create trigger t_b_tri_def \r\n 2 before insert on t_trigger_default\r\n 3 for each row\r\n 4 begin\r\n 5 :new.col := 'trigger';\r\n 6 end;\r\n 7 \/\r\nTrigger created.\r\nSQL> insert into t_trigger_default (id)\r\n 2 values (1);\r\n1 row created.\r\nSQL> select * from t_trigger_default;\r\n ID COL\r\n---------- ------------------------------\r\n 1 trigger\r\nSQL> create or replace trigger t_b_tri_def\r\n 2 before insert on t_trigger_default\r\n 3 for each row\r\n 4 begin\r\n 5 :new.col := nvl(:new.col, 'trigger');\r\n 6 end;\r\n 7 \/\r\nTrigger created.\r\nSQL> insert into t_trigger_default (id)\r\n 2 values (2);\r\n1 row created.\r\nSQL> select * from t_trigger_default;\r\n ID COL\r\n---------- ------------------------------\r\n 1 trigger\r\n 2 default\r\nSQL> insert into t_trigger_default (id, col)\r\n 2 values (3, '');\r\n1 row created.\r\nSQL> select * from t_trigger_default;\r\n ID COL\r\n---------- ------------------------------\r\n 1 trigger\r\n 2 default\r\n 3 trigger<\/pre>\n\u4ece\u8fd9\u4e2a\u4f8b\u5b50\u53ef\u4ee5\u770b\u51fa\uff0c\u65e0\u8bba\u662fDEFAULT\u503c\u8fd8\u662fTRIGGER\u90fd\u662f\u751f\u6548\u7684\uff0c\u53ea\u4e0d\u8fc7TRIGGER\u5728DEFAULT\u503c\u4e4b\u540e\u751f\u6548\u3002\u5f53\u4e00\u4e2a\u5217\u7684\u503c\u5728\u63d2\u5165\u65f6\u6ca1\u6709\u6307\u5b9a\u503c\uff0c\u90a3\u4e48DEFAULT\u503c\u5c31\u4f1a\u751f\u6548\uff0c\u5982\u679c\u6709\u89e6\u53d1\u5668\u4fee\u6539\u8fd9\u4e2a\u5217\u7684\u503c\uff0c\u90a3\u4e48\u8fd9\u4e2a\u4fee\u6539\u53d1\u751f\u5728DEFAULT\u503c\u751f\u6548\u4e4b\u540e\u3002\u4e00\u65e6\u5217\u8f93\u5165\u4e86\u503c\uff0c\u5219DEFAULT\u503c\u4e0d\u518d\u751f\u6548\u3002
\n\u800cAFTER\u89e6\u53d1\u5668\u662f\u65e0\u6cd5\u4fee\u6539\u5217\u7684\u503c\u7684\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4eca\u5929\u5728\u5199\u89e6\u53d1\u5668\u7684\u65f6\u5019\u7a81\u7136\u60f3\u5230\u8fd9\u4e00\u70b9\uff0c\u4e3a\u4e86\u9a8c\u8bc1\u60f3\u6cd5\uff0c\u505a\u4e86\u4e00\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u3002 \u5982\u679c\u4e00\u4e2a\u5b57\u6bb5\u62e5\u6709\u9ed8\u8ba4\u503c\uff0c\u4e14\u5305\u542b\u4e00\u4e2aBEFORE\u7684\u884c\u7ea7\u89e6\u53d1\u5668\uff0c\u5f53\u4e0d\u6307\u5b9a\u503c\u65f6\uff0c\u4e8c\u8005\u7684\u751f\u6548\u987a\u5e8f\u5982\u4f55\uff1a SQL> create table t_trigger_default (id number, col varchar2(30) default ‘default’); Table created. SQL> create trigger t_b_tri_def 2 before insert on t_trigger_default 3 for each row 4 begin 5 :new.col := ‘trigger’; 6 end; 7 \/ Trigger created. SQL> … Continue reading