模糊处理:CREATE TRIGGER 语句可以采用模糊处理的形式提交。 在模糊化语句中,只有触发器名称是可读的。 该语句的其余部分以不可读的方式进行编码,但可由数据库服务器进行解码。 可以通过调用 DBMS_DDL.WRAP 函数来生成模糊化的语句。 使用受保护选项创建触发器: 通常,具有 SECADM 权限的用户没
The rest of the statement is encoded in such a way that is not readable but can be decoded by the database server. Obfuscated statements can be produced by calling the DBMS_DDL.WRAP function. Creating a trigger with the SECURED option: Normally users with SECADM authority do not have ...
注意: DML:data manipulation language 数据操作语句: select update insert delete 需要提交与回滚事务增删改 DDL : data definition language: 数据库定义语句 create ,alter, drop DCL: data control language 数据库控住语句 grant deny revoke 设置更改数据库用户的角色或者权限 3.为什么要使用事务? 是为了保证数...
Another common trigger use is to save important original data, in its unchanged state, to maintain an audit trail or ensure that the original data remains accessible in the event of accidental changes. For example, the same HR application may contain a trigger that is executed when an employee...
(DBMS), a trigger is an SQL procedure that is executed when a record is added or deleted. It is used to maintain referential integrity in the database. A trigger may also execute a stored procedure. Triggers and stored procedures are built into DBMSs used in client/server environments. ...
CREATEORREPLACETRIGGERuser_audit_trigAFTERINSERTORUPDATEORDELETEONempDECLAREv_action VARCHAR2(24);BEGINIFINSERTINGTHENv_action :=' added employee(s) on ';ELSIF UPDATINGTHENv_action :=' updated employee(s) on ';ELSIF DELETINGTHENv_action :=' deleted employee(s) on ';ENDIF;DB...
dbms_output.put_line(‘ Difference ‘ || sal_diff); END; / The size of the Trigger should not exceed 32K. Important Points Trigger will work on DML operations, INSERT,DELETE,UPDATE BEFORE/AFTER key words. When trigger has to execute, we need to given in definition FOR EACH ROW => Tri...
EDB Postgres Advanced Server supports three variations of theALTER TRIGGERcommand. Use the first variation to change the name of a given trigger without changing the trigger definition: ALTERTRIGGER<name>ONRENAMETO<new_name> Use the second variation of theALTER TRIGGERcommand if the ...
and delete events against tables; Data Definition Language (DDL) triggers, which fire in response to CREATE, ALTER, and DROP statements; and logon triggers, which fire in response to LOGON events. DDL triggers can also fire in response to some system SPs that perform DDL-like operations....
UPDATEcustomersSETsalary=salary+500WHEREid=2; When a record is updated in the CUSTOMERS table, the above create trigger,display_salary_changeswill be fired and it will display the following result − Old salary: 1500 New salary: 2000 Salary difference: 500 ...