Third, attempt to drop the sales_employees view: DROP VIEW IF EXISTS sales_employees;Code language: SQL (Structured Query Language) (sql) Since the sales_employees_contacts view depends on the sales_employees view, it became invalid when you drop the sales_employees view. ...
execute immediate 'DROP VIEW ' || ObjName; end if; end if; if upper(ObjType) = 'SEQUENCE' then select count(*) into v_counter from user_sequences where sequence_name = upper(ObjName); if v_counter > 0 then execute immediate 'DROP SEQUENCE ' || ObjName; end if; end if; end; ...
drop materialized view [if exists] view_name; 4.1.4 查询 select * from mv_name; 4.2 PostgreSQL 4.2.1 创建 -- 创建视图CREATE MATERIALIZED VIEW [ IF NOT EXISTS ] table_name[ (column_name [, ...] ) ][ USING method ][ WITH ( storage_parameter [= value] [, ... ] ) ][ TABLESPAC...
--/beginjoe.PROC_DROPRESOURCEIFEXISTS('view','v01_bigint','cascade constraints');end;/ 当然 createorreplaceviewjoe.v01_bigintasselect*fromjoe.t_bigint; 可以直接创建和replace view,不用提前删除。这里只是为了说明调用的方法。
语法2:CREATE OR REPLACE VIEW 视图名称 AS 子查询 如果视图已经存在我们可以使用语法2来创建视图,这样已有的视图会被覆盖。 create or replace view empvd20 as select * from emp t where t.deptno = 20 不建议通过视图对表中的数据进行修改,因为会受到很多的限制。
SQL>grant create view toUSERNAME;SQL>grant unlimited tablespace toUSERNAME;SQL>grant createpublicsynonym toUSERNAME;SQL>grant droppublicsynonym toUSERNAME;SQL>create or replace directory dir_dumpas'/u01/oracle/backup';SQL>grant read,write on directory dir_dump toUSERNAME;SQL>ALTERPROFILEDEFAULTLIMIT...
SET NOCOUNT OFF USE pubs IF EXISTS (SELECT name FROM sysindexes WHERE name = 'au_id_ind') DROP INDEX authors.au_id_ind GO USE pubs CREATE INDE FILLFACTOR 中间级页 叶级页 0 一个可用项 100% 填满 1% -99 一个可用项 <= FILLFACTOR% 填满 100% 一个可用项 100% 填满 一个可用项是指页...
(CONNECT_DATA =(SERVICE_NAME = ORCL)))';--创建DB_LINKdroppublic database link "MARKETDATABAK";--删除DB_LINK 存储 索引 优化 in和exists in会先查询子 再查询外 exist 会先查外 再查子select*fromm t8_bond_deal_infowhereidin(selectIDfromt8_bond_deal_infowhereid >1);select*fromt8_bond...
drop role hr_db_obj; create role hr_db_obj; -- Grant object privilege to the db role. grant select, insert, update, delete on hr.employees to hr_db_obj; -- Grant db role to dynamic role. grant hr_db_obj to HROBJ; -- Create a security class with privilege view_sensitive_info,...
IF TABLE EXISTS DROP TABLE table_name; ``` 其中,`schema` 是可选的,表示表所在的用户名和模式名。`table_name` 是必选的,表示要创建的表名。`column1`、`column2` 等表示表中的列和列的数据类型、约束等属性。 ## 示例与实践 现在我们通过一个示例来演示如何使用 IF TABLE EXISTS 子句创建表。 假设...