create or replace view

A. Data dictionary:Oracle's data dictionary records the metadata of database management, which is the core file of life and death for a database. 1. The data dictionary is placed in the system table space, and the user is sys. 2. Describe the

Describe a table with DESC employeesFilter Duplicate department SELECT distinct DEPARTMENT_ID from EmployeesThree ways to alias: 1, Space 2, plus as 3, "" (the alias of multiple words must be separated by a space, or by an underscore)Condition

----Database objects: A collection of logical structures----synonyms: Aliases for existing objects/*function:Simplifying SQL statementshide the name and owner of an objectprovides public access to an objectCategory: */--public synonym: can be

/** Creating a database **/Create Database testdata;/**return to query OK; Indicates that the creation was successful.**//** Deleting a database **/Drop database testdata;/**return to query OK; Indicates a successful creation**//** shows the engines

1. Knowledge Points: Can be read against the following record screen view, sequence, index, Synonym Sql>--view: Virtual table sql>--View advantages: Simplify complex queries, limit data access (more banks), provide independent data, the same data

1. find information for all students[Sql]select * FROM studentRows affected : 0Time : 0.000s2. Identify all the people who have passed the test[Sql]select * from student where Studentno in (select Studentno from result where Studentresult > 60)Rows

Some say to upgrade the client, but I use the Oracle 11.2.0.3 export is not a problem, Oracle9 and 10 have this problem, please consider upgrading the client. Another approach to not upgrade clients: There is a problem with Oracle exporting

Data IndependencePersonally understand that early applications need data directly linked to the database table, if for some reason, need to modify the table structure, then it is likely to cause the application also yo make the appropriate changes.

Create a View In MySQL, the complete syntax for creating a view is as follows: CREATE [OR REPLACE] [algorithm = {UNDEFINED | MERGE | TempTable}]VIEW view_name [(column_list)]As Select_statement[With [cascaded | Local] CHECK OPTION Its

oracle| data First, Oracle's dictionary tables and views can basically be divided into three levels. 1.1 x$ Table This section of the table is the basis for the operation of the Oracle database, which is dynamically created by the Oracle application

Without the standardization process involved, it is very difficult for programmers to develop an application that can be used in a variety of languages. If possible, the translation process can be done in the database, so that developers have a lot

One, MySQL installation MySQL Downloads http://dev.mysql.com/downloads/mysql/ MySQL version selection MySQL feature custom selection installation Function Customization Selection Path Customization Selection Set Root user password

Create DATABASE link WzglConnect to MMCSG_GX (user name)Using ' (Description= (address_list= (address= (host=xx.xxx.xx.xxx (IP address)) (PROTOCOL=TCP) (port= port number))) (connect_ Data= (service_name= instance name))) ';1, if you need to create

Mysql View1. Introduction to the View1) Meaning of the view:A view is a virtual table. Unlike a table that contains data, a view contains only queries that retrieve data dynamically when used.2) Why use Views:Reuse SQL statements.simplifies complex

Views (view)A view is also known as a virtual table, which is a logical representation of a set of data.The view corresponds to a SELECT statement, and the result set is given a name, which is the name of the view.The view itself contains no data,

Shell scripting + MySQL database for enterprise-level session Border controller file parsing and alertingdirsx30001.sh process files, generate MySQL backup files in a way to import#/bin/bash# #环境变量path =/home/sbclog/sx30001# #由于抓取的日志文件中没有年份参数,

1. Why Use Views:To improve the reusability of complex SQL statements and the security of table operations (for example, the Payroll field does not want to show to all people who can view the results of the query), MySQL provides the view features.

Views ViewA view is one of the objects of a database. A view is also called a virtual table, which is essentially a SELECT statement.The result set of a SELECT statement is given a name that is the name of the view.Role:1. Complex queries can be

SQL CREATE View Statement What is a view?In SQL, a view is a table of visualizations based on the result set of an SQL statement.The view contains rows and columns, just like a real table. A field in a view is a field from a real table in one or

What is a view? ）1. A view is a database object, a virtual table that is exported from one or more data tables or views, and the data corresponding to the view is not really stored in the view, but is stored in the referenced data table, and the