fundamentals of database systems

Connection query: You can implement multiple table queries by using the Join operator. Connection is the main feature of relational database model, and it is also a sign that distinguishes it from other types of database management system.Common two link operators:1.join on2.union in the relational database management system, the relationship between the data

Database design is divided into requirements analysis, conceptual design, logical design and database physical design four parts.1. Demand Analysis:Stage Result: Requirement specification.2. Conceptual structure Design:Conceptual structure design is to synthesize, generalize and abstract the user's needs, and form a conceptual model independent of the specific DBMS.Conceptual structure design typically has

so will cause the engine to discard full table scans using the index, such as: Select ID from t where num=10 or num=20 You can query this:Select ID from t where num=10UNION ALLSelect ID from t where num=20 (The difference between Union and union all is that union automatically compresses duplicate results in multiple result sets, and union ALL displays all results, whether duplicates or not.) ) 5. If there is a stored procedure Proc1 (employee number, month) in MySQL to query the employee's sa

duplicates:0 warnings:0 2) Delete field mysql> ALTER TABLE student drop column sgender;Query OK, 0 rows affected (0.03 sec)records:0 duplicates:0 warnings:0 3) Modify the field type mysql> ALTER TABLE student Modify column remark varchar (100);Query OK, 0 rows affected (0.07 sec)records:0 duplicates:0 warnings:0 4) Modify the field name mysql> ALTER TABLE student change column sgender gender varchar (2)

convert.tostring () (String) From the results can be seen: converted to int , the rounding calculation, this and the display type conversion is different, before we use the display type conversion to convert 58.5 to int is the result of The value after the decimal point is discarded directly. Summary: The range of methods used for various conversionsImplicit type conversions: often used between numeric types, converting a numeric type with a small

:Select * from Xinxi where name= ' John Doe ' and nianling=2610, or ... "or"Select * from Xinxi where name= ' John Doe ' or nianling=2611, IN (...) In... Range ofColumn names are queried for which range to query.Select * from Xinxi where nianling in (21,22,23,24)Select * from Xinxi where name in (' John Doe ', ' Zhao Liu ')12, not...in (...) Not... Range ofSelect * from Xinxi where name is not in (' John Doe ', ' Zhao Liu ')13, wildcard% means any number of any character; Like, fuzzy query, when

Copyright NOTICE: This article is the original article of Bo Master, reprint annotated source http://blog.csdn.net/u0131427811. Super key, candidate key, primary key, foreign keyHyper-Key: A property set that uniquely identifies a tuple in a relationship is called a hyper-key of a relational pattern. A property can be used as a super-key, and multiple properties can be combined together as a super-key. The super-key contains the candidate and primary keys.candidate Key: is the least-key, that is

or negative currencies. In Microsoft SQL Server, the data type of the currency data isMoney and SmallMoney The Money data type requires 8 storage bytes, and the SmallMoney data type requires 4 bytes of storage. 　　 (7) Special data types Special data types include data types that were not previously mentioned. There are 3 unique types of data, namelyTimestamp, Bit and uniqueidentifier。The Timestamp is used to represent the sequence of SQL Server activities in a binary projection format. Timesta

1. Experimental Content1) Create a database with Management Studio University_mis2) Create a relational database base table using SQL statements:Student table Students (Sno,sname, semail,scredit,sroom);Teacher Table Teachers (tno,tname,temail,tsalary);Curriculum courses (CNO,CNAME,CCREDIT);Score Table reports (Sno,tno,cno,score);Where: Sno, Tno, CNO are table students, table teachers, table courses The pri

Label:2.1MySQL Getting Started 1) Download to mysql website. 2) Install mysql software 3) Use Verify success turn on cmd-- input mysql-u root-p Enter password return C:\users\apple>mysql-u root-p Enter Password: * * * Welcome to the MySQL Monitor. Commands End With; or \g. Your MySQL Connection ID is 2 Server version:5.5.40 MySQL Community Server (GPL) Copyright (c), the Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of the Oracle Corporation and/or i

95031 107Wang Liju1976/1/ at 95033 101Li June Man1976/2/ - 95033 109Wang Fang Men1975/2/Ten 95031 103Contacts male1974/6/3 95031 6rows selected SQL> SetServeroutput on; SQL> ExecuteHanqi (95031); Kuanming Wang Fang contacts PL/SqlprocedureSuccessfully completed v. Functions (function) Functions are constructed in a similar way to stored procedures CREATE OR REPLACE FUNCTION inch Number inch Number RETURN Number as number ; BEGIN C:=+ B; RETUR

that you are calling to change the value of a parameter, you must pass it by reference using the ref or out keyword.Note: Passing parameters by reference also uses a ref-decorated parameter when calling a method.Comparison value passing and reference passingIn summary, a value pass is a copy of the value of a variable that is passed to the method so that the parameter of the method is the same as the value of the argument. Modifying a parameter in a called method is also an update to the data o

Overview of Database Systems (third edition) A basic textbook of the database, published by the higher Education press. In order to deepen the basic knowledge of the databaseUnderstand, look over again, to further grasp the knowledge of the database to lay the groundwork for learning.The book is divided into four parts

Tags: system ons open with sites Mmu tin for EveCS 265:research Topics in Database SystemsAnnouncements Quiz 3 would be posted. Good luck! Quiz 2 has been posted. Good luck! Here's the history of a Paper this was mentioned in the Project handout. Paper Survey for the first third of the course. Quiz 1 has been posted. Good luck! Final Project assignment is now available. If you ne ed an EECS account for your project, ap

To bring up the database, the first company to think of, is usually oracle. The company was founded in 1977 and was originally a company specializing in the development of databases. Oracle has a leading position in the database field. In 1984, the relational database was first transferred to the desktop computer. Then, the next version of Oracle, Version 5, pion

DB2 is a product of IBM, originating from System R and system r*. He supports from PCs to UNIX, from minicomputer to Mainframe, from IBM to non-IBM (HP and SUN UNIX System, etc.) a variety of operating platforms. He can run either independently on the host or in a client/server environment. which service Platform can be os/400,aix,os/2,hp-unix,sun-solaris and other operating systems, the client platform can be OS/2 or Windows, Dos, AIX, hp- UX, SUN So

Tags: style SP file data on new management as databaseThe difference between a relational database system file system is:First, the overall data of a relational database is structured and described by a relational data model, which is fundamentally different from the file system. (data models include: Data structures, operations, and integrity constraints)Secondly, the relational

Oracle Microsoft SQL server2005 Sybase Informix DB2 Ingers Microsoft Access Visual FoxPro MySQL OracleOracle is one of the earliest commercial relational database management systems. It is also a widely used and powerful database management system. As a general database management systemThe entire d

Tags: language keyword trigger copy table market share form beauty of memory data electronics1 Requirements What are some of the database management Systems (DBMS) on the market today, and what are their characteristics? What are the advantages and disadvantages between them? What are their use cases, respectively? 1.1 What kind of database management system (DBM

1. Self-increasing primary key The primary advantage of the Self-increasing primary key is performance. Early database systems often used some numbers, such as ID card numbers and company numbers, as the primary key of the database table. However, soon, you will find the disadvantages. For example, in the early Hospital Management System, the ID card number