Update with CASE StatementThis example demonstrates how to update rows conditionally using a CASE statement: update_with_case.sql -- CREATE TABLE books ( -- book_id INTEGER PRIMARY KEY, -- title VARCHAR(100) NOT NULL, -- author VARCHAR(100) NOT NULL, -- genre VARCHAR(50) NOT NULL, -...
if-else, case, etc. TheCASEstatement is one of the conditional expressions that is used to create conditional queries. PostgreSQL allows us to use the WHEN-THEN case, if-else statements, etc. with the CASE statement to create or formulate a query/expression. ...
任何不获取FOR UPDATE锁的UPDATE也会获得这种锁模式。 FOR SHARE 共享 行为与FOR NO KEY UPDATE类似,不过它在每个检索到的杭上获得一个共享锁而不是排他锁。 一个共享锁会阻塞其他食物在这些行上执行UPDATE、DELETE、SELECT FOR UPDATE或者SELECT FOR NO KEY UPDATE,但是它不会阻止它们执行SELECT FOR SHARE或者SELE...
使用CREATE ROLE 或 CREATE USER(CREATE USER 是 CREATE ROLE 的一个带有登录权限的别名)语句来创建新用户。 CREATEUSERreadonly_userWITHPASSWORD'your_secure_password'; 注意:从 PostgreSQL 10 开始,建议使用 CREATE ROLE 和 ALTER ROLE ... LOGIN 来创建用户,因为 CREATE USER 只是 CREATE ROLE 的一个快捷方式。
表触发器的创建分类 :(before | after) (INSERT | UPDATE | DELETE) (FOR EACH ROW) (WHEN NEW.? and,or OLD.? ... other boolean express ...)(before | after) (INSERT | UPDATE | DELETE | TRUNCATE) (FOR EACH STATEMENT) (WHEN BOOLEAN express except NEW or OLD or columns) 视图...
In this case, you can use the PostgreSQL UPDATE join. Here’s the basic syntax of the UPDATE join statement: UPDATE table1 SET table1.c1 = new_value FROM table2 WHERE table1.c2 = table2.c2; To join a table (table1) with another table (table2) in the UPDATE statement, you ...
#krb_caseins_users = off # 设置 Kerberos 和 GSSAPI 用户名是否应区分大小写。默认是off(区分大小写) # - TCP Keepalives - # see "man 7 tcp" for details #tcp_keepalives_idle = 0 # 指定不活动多少秒之后通过 TCP 向客户端发送一个 keepalive 消息。
要评估一个用户是否在权限上持有赋权选项,给权限键字附加 WITH GRANT OPTION;比如 'UPDATE WITH GRANT OPTION'。 3. 模式可视性查询函数: 那些判断一个对象是否在当前模式搜索路径中可见的函数。 如果一个表所在的模式在搜索路径中,并且没有同名的表出现在搜索路径的更早的地方,那么就说这个表视可见的。 它等效...
self.update_lock(True): msg = self.process_manual_failover_from_leader() if msg is not None: return msg # check if the node is ready to be used by pg_rewind self._rewind.ensure_checkpoint_after_promote(self.wakeup) if self.is_standby_cluster(): # in case of standby cluster we ...
The result value of this expression is a Boolean that tells whether the operation (INSERT, UPDATE, DELETE, or SELECT) for the final result row should be executed or not. It corresponds to the WHERE clause of an SQL statement. the join tree...