使用触发器(Trigger):可以创建一个BEFORE UPDATE触发器,当更新操作发生时,触发器会检查是否更新了指定的列,并在满足条件时阻止更新操作。触发器可以使用PL/pgSQL等编程语言编写,具体实现如下: 代码语言:sql 复制 CREATEORREPLACEFUNCTIONprevent_column_update()RETURNSTRIGGERAS$$BEGIN
CREATE[CONSTRAINT]TRIGGERname{BEFORE|AFTER|INSTEADOF}{event[OR...]}ONtable_name[FROMreferenced_table_name][NOTDEFERRABLE|[DEFERRABLE][INITIALLYIMMEDIATE|INITIALLYDEFERRED]][REFERENCING{{OLD|NEW}TABLE[AS]transition_relation_name}[...]][FOR[EACH]{ROW|STATEMENT}][WHEN(condition)]EXECUTE{FUNCTION|PROCED...
UPDATE, or DELETE operation, either once per modified row, or once per SQL statement.UPDATE triggers can moreover be set to fire only if certain columns are mentioned in the SET clause of the UPDATE statement.Triggers can also fire for TRUNCATE statements.If a trigger event occurs, the tri...
CREATE TRIGGER update_timestamp_triggerBEFORE UPDATE ON your_tableFOR EACH ROWEXECUTE PROCEDURE update_timestamp();from sqlalchemy import Column, Integer, String, DateTime, func from db.base_class import Base class Demo(Base): # 表的名字: __tablename__ = 'demo' id = Column(Integer, autoin...
权限类型包括:SELECT、INSERT、UPDATE、DELETE、TRUNCATE、REFERENCES、TRIGGER、CREATE、CONNECT、TEMPORARY、EXECUTE、USAGE、SET、ALTER SYSTEM。 详情如下: SELECT 允许从表、视图、具体化视图或其他类似表的对象的任何列或特定列执行 SELECT 操作。 还允许使用 COPY TO。
CREATE OR REPLACE TRIGGER "BIZBENIFITRATELOG_TR" BEFORE INSERT OR UPDATE OR DELETE ON BIZBENIFITRATELOG referencing new as new old as old FOR EACH ROW declare i number(10); ii number(10); opttype CHAR(1); dataid varchar2(32);
CREATE TRIGGER trigger_name[BEFORE|AFTER]UPDATE OF column_name ON table_name[--触发器逻辑...]; 实例 让我们假设一个情况,我们要为被插入到新创建的 COMPANY 表(如果已经存在,则删除重新创建)中的每一个记录保持审计试验: runoobdb=#CREATE TABLE COMPANY(ID INT PRIMARY KEY NOT NULL,NAME TEXT NOT NUL...
CREATE TRIGGER trigger_name ON { table | view } [ WITH ENCRYPTION ] { { { FOR | AFTER | INSTEAD OF } { [ INSERT ] [ , ] [ UPDATE ] } [ WITH APPEND ] [ NOT FOR REPLICATION ] AS [ { IF UPDATE ( column ) [ { AND | OR } UPDATE ( column ) ] ...
UPDATE:该权限允许对表或是或是表上特定的列或是视图进行更新操作。 DELETE:该权限允许对表或是视图进行删除数据的操作。 TRUNCATE:允许对表进行清空操作。 REFERENCES:允许给参照列和被参照列上创建外键约束。 TRIGGER:允许在表上创建触发器。 CREATE:对于数据库,允许在数据库上创建Schema;对于Schema,允许对Schema上创...
UPDATE 语法 命令语法 [ WITH [ RECURSIVE ] with_query [, ...] ] UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ] SET { column_name = { expression | DEFAULT } | ( column_name [, ...] ) = [ ROW ] ( { expression | DEFAULT } [, ...] ) | ( column_name [, .....