在PostgreSQL 中,可以使用 CREATE VIEW 语句来创建视图。 在PostgreSQL 中,视图是一种虚拟表,它基于 SQL 查询的结果集。视图并不存储数据,而是每次引用时动态生成数据。创建视图的基本语法如下: sql CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW view_n
PostgreSQL 创建视图的语法为:CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW `name` [ ( column_name [, ...] ) ] [ WITH ( view_option_name [= view_option_value] [, ... ] ) ] AS query [ …
1. CREATE OR REPLACE VIEW 按照"CREATE OR REPLACE VIEW" 关键字搜索,这部分代码在ATExecCmd函数(tablecmds.c文件)。可以看到它对应的命令类型叫AT_AddColumnToView,对应操作为调用ATExecAddColumn函数为视图新加列。 /* * ATExecCmd: dispatch a subcommand to appropriate execution routine */ static void AT...
create or replace view emp_details_view as select e.employee_id, e.job_id, e.manager_id, e.department_id, d.location_id, e.first_name, e.last_name, e.salary, e.commission_pct, d.department_name, j.job_title, e.hire_date from employees e join departments d on (e.department_id ...
createindexidx_student_classid_stu_dateonstudent(stu_classid,stu_date); explainanalyze-- create or replace view view_student asselect/*+ parallel(s 4 hard) IndexOnlyScan(s idx_student_classid_stu_date) */sc.cls_id,count(distinctstu_date)fromstudent sleft joinstu_class scons.stu_classid...
create or replace viewvw_usersasselect * from users; 二、通过定义规则来更新视图 create rulevw_users_updas on update tovw_usersdo instead updateusers set user_email=New.user_email; updatevw_userssetuser_email='zhangsan@163.com'whereid=1; ...
CREATE [OR REPLACE] [TEMP | TEMPORARY] [RECURSIVE] VIEW name [(column_name[,...])] [WITH (view_option_name [=view_option_value][,...])] AS query [WITH [CASCADED | LOCAL] CHECK OPTION] 1. 创建普通视图 CREATE VIEW vw_employee AS SELECT empid,begindate,enddate,companyname,responsibi...
CREATE VIEW:#定义一个查询的视图。 CREATE OR REPLACE VIEW:#如果已经存在一个同名视图,该视图会被替换(限制:只能在原视图基础上增加字段,不能减少字段,且增加字段顺序只能排在最后)。 TEMPORARY|TEMP:#视图被创建为一个临时视图。在当前会话结束时会自动删掉。当临时视图存在时,具有相同名称的已有永久视图对当前会...
CREATE [OR REPLACE] TRIGGER trigger_name {BEFORE | AFTER } {INSERT | DELETE | UPDATE [OF column [, column …]]} [OR {INSERT | DELETE | UPDATE [OF column [, column …]]}...] ON [schema.]table_name | [schema.]view_name
SYSID uid | [ ENCRYPTED | UNENCRYPTED ] PASSWORD 'password' | CREATEDB | NOCREATEDB | CREATEUSER | NOCREATEUSER | IN GROUP group_name [, ...] | VALID UNTIL 'abs_time'CREATE VIEW定义一个视图。CREATE [ OR REPLACE ] VIEW name [ ( column_name [, ...] ) ] AS query...