create or replace view

View Overview:– Create, modify, and retrieve data from a view– Data Manipulation Language (DML) operations on the view– Delete ViewDatabase objects Object objects Description description Table tables A basic

A view is a table that is exported from a table or view, or a table that is exported from more than one table or view. A view is a virtual table in which the database does not actually store the data that corresponds to the view, only the definition

View The operation of the view can not only simplify the query, but also improve the security View: essence is a virtual table whose content is similar to a real table and contains a series of column and row

If it is Oracle 10g above a wm_concat function can be solved.It's a bit of a hassle if you're under Oracle 9i.The table structure is as follows:NAME Null Type--------------------------------- -----n_sec _code

1.Create userSql>--For example, create a user named Xiaoming with a password of A123sql> Create user xiaomingidentified by A123;The user has created.Sql> Show UserUSER is "SYS"2.granting permissions to usersSql>--grant permissions to User

A view is a virtual table that does not occupy physical space because the definition statements of the view itself are stored in the data dictionary. The data in the view is obtained from one or more actual tables.Materialized views: Also into a

One, Data update operationDML syntax includes two main content: Query and update, update mainly include: Add data, modify data, delete data. These operations are inseparable from the query.1. Add DataSyntax: INSERT into table name [(Field name 1,

Turn from:http://blog.csdn.net/wenzhongyan/article/details/50315473http://blog.csdn.net/ojerryzuo/article/details/539270571. Convert clob field to VARCHAR2 type by DBMS_LOB.SUBSTR ()When querying the Dba_stat_extensions view, where the extension

First, the ViewA view is a virtual data table that does not store the data itself, but rather provides a logical presentation of the data.1. Create a ViewCreate View Stu_view asselect s1.id, S1.name, S2.room, s2.stay_timefrom student s1, stay

Oracle 10 Gb dmp how to import 9i Problem description: How to migrate database objects in oracle 10 Gb to 9i. the 10g and 9i servers are respectively built on two machines in the LAN and can access each other. problem Analysis: Some information has

The use trap OF the INSTEAD trigger for views associated with more than two tables, Oracle cannot tell which table should be updated, and the INSTEAD trigger meets our requirements for the view DML, the display tells Oracle which table www.2cto.com

I. Introduction to a view, role, and Advantages 1. What is a view? A. A view is a virtual table that is exported from one or more tables in the database. the database only stores view definitions, but does not Store View data. The data is stored in

Oracle knowledge point Summary 3 (subquery) 1. Use of subquery 1. insert use of subquery when inserting data in insert, be sure not to add the Vaules keyword. SQL> create table copy_dep as select * from departments;Table created.SQL> truncate

My MYSQL learning experience (11) my MYSQL learning experience (11) My experiences with MYSQL (1) My experiences with MYSQL (2) My experiences with MYSQL (III) My experiences with MYSQL (4) My experiences with MYSQL (5) My experiences with MYSQL (6)

My MYSQL learning experience (11) my MYSQL learning experience (11) My experiences with MYSQL (1) My experiences with MYSQL (2) My experiences with MYSQL (III) My experiences with MYSQL (4) My experiences with MYSQL (5) My experiences with MYSQL (6)

MYSQL Getting started: Basic View operations bitsCN.com MYSQL Getting started: Basic View operations Related links: MYSQL: Basic operations Http: // database/201212/173868 .html MYSQL 2: use regular expressions to search Http: // database/201212/17

Run the SELECT statement in the following SQL statement separately. If it is used for CREATEVIEW, an error is returned. The SELECT statement in the following SQL statement is executed independently. If it is used to CREATE VIEW, an error is returned.

Oracle trigger 5-Instead of trigger Oracle trigger 4-database event trigger http://www.bkjia.com/database/201304/201423.html The Instead of trigger can be used to insert, update, delete, and merge tables in a view composed of more than one table.

Common Oracle functions: nvl/nullif/case when/wm_concat/replace 1. nvl function nvl converts a null value to an actual value. The data type can be date, number, character, and data type must match: nvl (commision, 0) nvl (hiredate, '01-JAN-87 ') nvl

In the process of database development, it is often necessary to convert rows into columns or convert columns into rows to display data. However, when creating a table structure, we often cannot store data according to the display requirements,