Database Modelling with ERwin
... • “Always” use Integer and Identity(1,1) for Primary Keys. Use UNIQUE constraint for other columns that needs to be unique, e.g. “RoomNumber” • Specify Required Columns (NOT NULL) – i.e., which columns that need to have data or not ...
... • “Always” use Integer and Identity(1,1) for Primary Keys. Use UNIQUE constraint for other columns that needs to be unique, e.g. “RoomNumber” • Specify Required Columns (NOT NULL) – i.e., which columns that need to have data or not ...
The Askew Wall or Date and Darwen`s Database Dream
... Defining the order means defining it for every query operator, including FROM and UNION, which thus fail to be commutative (as they should be, as relational counterparts of AND and OR). Are they associative? The correct approach is to map columns to variables by name, not by order. ...
... Defining the order means defining it for every query operator, including FROM and UNION, which thus fail to be commutative (as they should be, as relational counterparts of AND and OR). Are they associative? The correct approach is to map columns to variables by name, not by order. ...
Title Slide No more than 2 lines
... Natural key vs. surrogate key. Clustered key doesn’t have to be the primary key, but often will be. • Unique constraints can enforce additional important business rules. ...
... Natural key vs. surrogate key. Clustered key doesn’t have to be the primary key, but often will be. • Unique constraints can enforce additional important business rules. ...
BCS Higher Education Qualifications Professional Graduate Diploma
... log. This shall include the latest version number, date of the amendment and the changes made. The purpose is to identify quickly what changes have been made. Version Number V1 V1.a ...
... log. This shall include the latest version number, date of the amendment and the changes made. The purpose is to identify quickly what changes have been made. Version Number V1 V1.a ...
Given a query workload
... query template in advance allows us to propose better solutions for balancing load across multiple servers in the scenario of web applications, above and beyond what is supported for traditional applications. Prior knowledge of all of the incoming query templates and the workload give us the ability ...
... query template in advance allows us to propose better solutions for balancing load across multiple servers in the scenario of web applications, above and beyond what is supported for traditional applications. Prior knowledge of all of the incoming query templates and the workload give us the ability ...
Relational Databases
... As this approach should not affect the Legacy I.S. at all, it has a good fall back position if the Target I.S. fails. It could mean that several years of developing the Target I.S. are lost, but the company can survive and continue to trade, using the Legacy I.S. However a correctly managed user mig ...
... As this approach should not affect the Legacy I.S. at all, it has a good fall back position if the Target I.S. fails. It could mean that several years of developing the Target I.S. are lost, but the company can survive and continue to trade, using the Legacy I.S. However a correctly managed user mig ...
Interacting with the Oracle Server
... EMP table who are Analysts. •Example DECLARE v_sal_increase emp.sal%TYPE := 2000; BEGIN UPDATE emp SET sal = sal + v_sal_increase WHERE job = 'ANALYST'; END; ...
... EMP table who are Analysts. •Example DECLARE v_sal_increase emp.sal%TYPE := 2000; BEGIN UPDATE emp SET sal = sal + v_sal_increase WHERE job = 'ANALYST'; END; ...
The Entity-Relationship Model
... Should address be an attribute of Employees or an entity (connected to Employees by a relationship)? Depends upon the use we want to make of address information, and the semantics of the data: • If we have several addresses per employee, address must be an entity (since attributes cannot be setval ...
... Should address be an attribute of Employees or an entity (connected to Employees by a relationship)? Depends upon the use we want to make of address information, and the semantics of the data: • If we have several addresses per employee, address must be an entity (since attributes cannot be setval ...
ppt
... • Suppose that you want to build an university database. It must store the following information: – Entities: Students, Professors, Classes, Classrooms – Relationships: Who teaches what? Who teaches where? Who teaches whom? ...
... • Suppose that you want to build an university database. It must store the following information: – Entities: Students, Professors, Classes, Classrooms – Relationships: Who teaches what? Who teaches where? Who teaches whom? ...
SSMS SQL Server Management System
... – Before we can add data to our database, we'll need to create at least one table. ...
... – Before we can add data to our database, we'll need to create at least one table. ...
SQL - bYTEBoss
... • SQL stands for Structured Query Language. It was developed in the 1970s at IBM (Big Blue) as a way to provide users with a standard method of selecting data from many different database formats. • SQL is used to gain access to the relations and the desired set of data and the programmer does not h ...
... • SQL stands for Structured Query Language. It was developed in the 1970s at IBM (Big Blue) as a way to provide users with a standard method of selecting data from many different database formats. • SQL is used to gain access to the relations and the desired set of data and the programmer does not h ...
Cost-based query optimization
... – Cost of scanning disk segment containing tuples – Cost models for different index access methods (tree structures hashing) – Cost models for different join methods – Cost of sorting intermediate results ...
... – Cost of scanning disk segment containing tuples – Cost models for different index access methods (tree structures hashing) – Cost models for different join methods – Cost of sorting intermediate results ...
An Overview of Data Models
... – relational database schema (or simply, database schema) a set of schemas for the relations of a database ...
... – relational database schema (or simply, database schema) a set of schemas for the relations of a database ...
students - Personal Home Pages (at UEL)
... • SQL (often pronounced “sequel”) stands for Structured Query Language • A set of special reserved words organised in a specific order used exclusively for communicating with a database • All major databases use SQL although there can be slight differences in the syntax ...
... • SQL (often pronounced “sequel”) stands for Structured Query Language • A set of special reserved words organised in a specific order used exclusively for communicating with a database • All major databases use SQL although there can be slight differences in the syntax ...
Chapter 6
... a. Click the join line connecting the two tables and press the Del key b. Double click the join line c. Click the join field and press Del d. All of the above ...
... a. Click the join line connecting the two tables and press the Del key b. Double click the join line c. Click the join field and press Del d. All of the above ...
Lecture Notes - Department of Computer Science
... The Relational Database The Structured Query Language Single-Table Queries Multiple-Table Queries Functions ...
... The Relational Database The Structured Query Language Single-Table Queries Multiple-Table Queries Functions ...
Relational Database: A Practical Foundation
... The set Person is a relation: Person ⊆ W(Personal Number) • W(Name) • W(Surname) • W(Location) above the set of the attributes of the entity set Person. A entity is a instance, like the name Werner or the Location Ankara. Entitys with same properties are the entity set. Attributes are this propertie ...
... The set Person is a relation: Person ⊆ W(Personal Number) • W(Name) • W(Surname) • W(Location) above the set of the attributes of the entity set Person. A entity is a instance, like the name Werner or the Location Ankara. Entitys with same properties are the entity set. Attributes are this propertie ...
Database
... • Data can be accessed from different sites as well as the local site • Although each site has complete control over its local data, there is global control through the internet ...
... • Data can be accessed from different sites as well as the local site • Although each site has complete control over its local data, there is global control through the internet ...
MINFILE/vax INTRODUCTION MINFILE/vax DATABASE DESIGN
... Data diskettes, arranged in standard ASCII format files, contain the entire database for each map sheet. The files, once loaded onto a hard disk, are processible by common database management programs or by MINFILE/pc, a custom search program developed by the Branch (see MINFILE/pc Pamphlet). A util ...
... Data diskettes, arranged in standard ASCII format files, contain the entire database for each map sheet. The files, once loaded onto a hard disk, are processible by common database management programs or by MINFILE/pc, a custom search program developed by the Branch (see MINFILE/pc Pamphlet). A util ...
Database
... • Data can be accessed from different sites as well as the local site • Although each site has complete control over its local data, there is global control through the internet ...
... • Data can be accessed from different sites as well as the local site • Although each site has complete control over its local data, there is global control through the internet ...
Note 01
... New queries requires new/modified programs • Access Control and Security Who can and cannot access files, fields… Access different portions of a file • Recovery ...
... New queries requires new/modified programs • Access Control and Security Who can and cannot access files, fields… Access different portions of a file • Recovery ...
Relational model
The relational model for database management is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by Edgar F. Codd. In the relational model of a database, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.Most relational databases use the SQL data definition and query language; these systems implement what can be regarded as an engineering approximation to the relational model. A table in an SQL database schema corresponds to a predicate variable; the contents of a table to a relation; key constraints, other constraints, and SQL queries correspond to predicates. However, SQL databases deviate from the relational model in many details, and Codd fiercely argued against deviations that compromise the original principles.