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Database Concepts
Database Concepts

... DISTRIBUTED DATABASE AND DDBMS ...
1 Chapter Overview Preparing to Upgrade Performing a Version
1 Chapter Overview Preparing to Upgrade Performing a Version

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No Slide Title

... Source: Database System Concepts, Silberschatz etc. 2006 ...
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Slide Template - Eastern Michigan University
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...  With SCN, SQL statements always read a consistent set of values; those that were committed at or before the time the statement was started  Oracle only reads committed changes; it will never reads dirty data ...
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...  With SCN, SQL statements always read a consistent set of values; those that were committed at or before the time the statement was started  Oracle only reads committed changes; it will never reads dirty data ...
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... they want to find out which county had the most accidents, but they also want to be able to see – at the same time –whether the majority of them were self-inflicted or not. The problem is that the query we just ran won’t give you both answers at the same time. Notice that if you sort this last query ...
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... two expressions generate the same set of tuples on every legal database instance  In SQL, inputs and outputs are multisets (where the order is not ...
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... In parsing data, one problem occurred. Every row should represent one specific detail, but there were cases, in which information for feature component attribute contained a table with options. So it was necessary to find a solution, how to distinguish these cases and then process it in a correct w ...
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... ATTENDANCE, and its dimension tables are DATE, ROOM, LECTURER, STUDENT and COURSE; HOLIDAY is a subdimension of DATE, and DEPARTMENT is a subdimension of LECTURER, STUDENT and COURSE. For clarity of the figure we have omitted the labels on edges, which for each edge between two tables is the interse ...
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... an appropriate answer. Of course, this query was written with some obvious knowledge of how the graph is laid out within our database. In Section 4.2 we discuss how an end user can discover the structure of the database. Value comparisons are made after two objects have been coerced into comparable ...
Chapter 9 Slides
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Overview and History of Databases and Transactions

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Week 13 - Pravin Shetty > Resume
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... Divide your information into tables regarding main subjects or entities. Decide which columns will take place in each table (eg. Surname and StartDate for EMPLOYEES table) Decide the primary keys for all tables. A primary key is used to define a record specifically (eg. Province_code in PROVINCES ta ...
IOSR Journal of Computer Engineering (IOSR-JCE)
IOSR Journal of Computer Engineering (IOSR-JCE)

... which they expire and must be changed before account login is again acceptable. A balanced period can be established during which each effort to login to the database account acquire a warning message to change the password. If it is not changed by the end of that duration then the account is locked ...
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... Embedded SQL Programming Allows complex combinations of database operations to be naturally specified Also provides support for conditionals, iteration, exceptions, procedures, functions, packages, triggers, etc. ...
Lecture 14: Oh mighty Isis!
Lecture 14: Oh mighty Isis!

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worksheet for Chapter 19 - library database
worksheet for Chapter 19 - library database

...  Each table will need a key field to uniquely identify one record from another. In this case the key field will be BorrowerID. Click the BorrowerID row and select Edit, Primary Key from the menu. A small key icon will appear indicating that this is now the primary key. You can also write this in th ...
COSI 127b Introduction to Database Systems
COSI 127b Introduction to Database Systems

... set balance = balance  1.06 where balance > 10000 update account set balance = balance  1.05 where balance  10000 The order is important Can be done better using the case statement (next slide) CMSC424, Spring 2005 ...
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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.
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