(A) R
... Boyce-Codd Normal Form（BC范式） A relation schema R is in BCNF with respect to a set F of functional dependencies if for all functional dependencies in F+ of the form , where R and R, at least one of the following holds: is trivial (i.e., ) is a superkey for R ...
... Boyce-Codd Normal Form（BC范式） A relation schema R is in BCNF with respect to a set F of functional dependencies if for all functional dependencies in F+ of the form , where R and R, at least one of the following holds: is trivial (i.e., ) is a superkey for R ...
Flat File Database
... • An index speeds up access for a particular database request by creating an index table that provides quick navigation of the indexed information. • Slices ca be created on a element type name (s) for which frequent access is anticipated. • A combination of element type names and attribute values c ...
... • An index speeds up access for a particular database request by creating an index table that provides quick navigation of the indexed information. • Slices ca be created on a element type name (s) for which frequent access is anticipated. • A combination of element type names and attribute values c ...
Coordinating Peer-to-Peer Information Sources
... finite number of possible relation extensions (closed world assumption). Define relational multi-context system as a
family of relational languages (one per database) with
a generalized relational theory (in T) and set of
coordination formulas (in R).
Prove that for any relational multi-co ...
... finite number of possible relation extensions (closed world assumption). Define relational multi-context system
Continuous Queries and Publish/Subscribe
... Continuous Queries What does ‘continuous’ mean? (Continuous Semantics) The results of a continuous query is the set of data that would be returned if the query were executed at every instant in time. ...
... Continuous Queries What does ‘continuous’ mean? (Continuous Semantics) The results of a continuous query is the set of data that would be returned if the query were executed at every instant in time. ...
SQL
... • No condition on tuple selection • Example - query 9 • More than one relation in FROM clause means cross product • Example - query 10 • Similar to relational algebra cross product PROJECT combination Jane Reid, BSc/IT DB, QMUL, 28/1/02 ...
... • No condition on tuple selection • Example - query 9 • More than one relation in FROM clause means cross product • Example - query 10 • Similar to relational algebra cross product PROJECT combination Jane Reid, BSc/IT DB, QMUL, 28/1/02 ...
Structured Database Running on Appaserver
... Structured databases can grow to hundreds of tables. Each table needs the select, insert, update, and delete operation. Historically, a developer would have to write each operation for each table. On the other hand, Appaserver has a module for each operation. So development is nothing more than addi ...
... Structured databases can grow to hundreds of tables. Each table needs the select, insert, update, and delete operation. Historically, a developer would have to write each operation for each table. On the other hand, Appaserver has a module for each operation. So development is nothing more than addi ...
CS 245: Database System Principles
... by character strings or integers – Value differences: The color black might be represented by an integer code, the string BLACK, or the code BL – Semantic differences: One dealer distinguish station wagon from minivans, while another doesn’t – Missing values: A source does not record information tha ...
... by character strings or integers – Value differences: The color black might be represented by an integer code, the string BLACK, or the code BL – Semantic differences: One dealer distinguish station wagon from minivans, while another doesn’t – Missing values: A source does not record information tha ...
MySQL Quick Guide - San Francisco State University
... • Use a text editor to create a file with SQL commands and save it with extension .txt • To run the command file: – SOURCE commandFileName.txt • Ex: mysql> source c:\MySQLCommand.txt Note: Use the “/” for Windows mysql> source c:\teaching\475\ProcShowCustomers.txt; ...
... • Use a text editor to create a file with SQL commands and save it with extension .txt • To run the command file: – SOURCE commandFileName.txt • Ex: mysql> source c:\MySQLCommand.txt Note: Use the “/” for Windows mysql> source c:\teaching\475\ProcShowCustomers.txt; ...
25SpL7TranslatingERDiagram - Department of Computer Science
... • Do not create a table for the relationship • Add information columns that would have been in the relationship's table to the table of the entity with the key constraint • What is the disadvantage of this method? • What is the advantage of this method? ...
... • Do not create a table for the relationship • Add information columns that would have been in the relationship's table to the table of the entity with the key constraint • What is the disadvantage of this method? • What is the advantage of this method? ...
mod-C
... An expression such as “head–>name” is called a path expression Path expressions help avoid explicit joins If department head were not a reference, a join of departments with people would be required to get at the address Makes expressing the query much easier for the user ...
... An expression such as “head–>name” is called a path expression Path expressions help avoid explicit joins If department head were not a reference, a join of departments with people would be required to get at the address Makes expressing the query much easier for the user ...
XML
... All subelements that occur only once become attributes – For text-valued subelements, store the text as attribute value – For complex subelements, store the id of the subelement Subelements that can occur multiple times represented in a separate table – Similar to handling of multivalued attribu ...
... All subelements that occur only once become attributes – For text-valued subelements, store the text as attribute value – For complex subelements, store the id of the subelement Subelements that can occur multiple times represented in a separate table – Similar to handling of multivalued attribu ...
the relational database model: introduction
... of its being a foreign key in that relation. Later in the book, we will discuss database design issues in detail. But for now, note that when building a one-to-many relationship into a relational database, it will always be the case that the unique identifier of the entity on the “one side” of the r ...
... of its being a foreign key in that relation. Later in the book, we will discuss database design issues in detail. But for now, note that when building a one-to-many relationship into a relational database, it will always be the case that the unique identifier of the entity on the “one side” of the r ...
Integrity Constraints
... tasks automatically when certain conditions are met. As an illustration, suppose that, instead of allowing negative account balances, the bank deals with overdrafts by setting the account balance to zero, and creating a loan in the amount of the overdraft. The bank gives this loan a loan number iden ...
... tasks automatically when certain conditions are met. As an illustration, suppose that, instead of allowing negative account balances, the bank deals with overdrafts by setting the account balance to zero, and creating a loan in the amount of the overdraft. The bank gives this loan a loan number iden ...
original - Kansas State University
... All subelements that occur only once can become relation attributes For text-valued subelements, store the text as attribute value For complex subelements, can store the id of the subelement ...
... All subelements that occur only once can become relation attributes For text-valued subelements, store the text as attribute value For complex subelements, can store the id of the subelement ...
on the integration of ir and databases
... A structuring primitive, or structure for short, combines known types to create a structured type. Structures can be used recursively. The set, bag, and tuple are well-known structuring primitives that are provided in all OO data models. The MOA kernel supports a generic notion of orthogonal structu ...
... A structuring primitive, or structure for short, combines known types to create a structured type. Structures can be used recursively. The set, bag, and tuple are well-known structuring primitives that are provided in all OO data models. The MOA kernel supports a generic notion of orthogonal structu ...
1. Which TCP/IP port does SQL Server run on?
... redundant data. It is sometimes necessary because current DBMSs implement the relational model poorly. A true relational DBMS would allow for a fully normalized database at the logical level, while providing physical storage of data that is tuned for high performance. De-normalization is a technique ...
... redundant data. It is sometimes necessary because current DBMSs implement the relational model poorly. A true relational DBMS would allow for a fully normalized database at the logical level, while providing physical storage of data that is tuned for high performance. De-normalization is a technique ...
Overview of Triggers+DB : Opportunities and Issues
... DBMS: hard coded into kernel DBMS services: enhances database functionality External applications: creating triggers specific to application ...
... DBMS: hard coded into kernel DBMS services: enhances database functionality External applications: creating triggers specific to application ...
Lab For LU05 – SQL Programming Views, Stored Procedures
... difference between the logical model and the internal model is the latter is actually implemented in a DBMS. Notice, that although not represented in the diagram, the check constraints, unique constraints, and default values all have all been implemented in the database schema just like they were in ...
... difference between the logical model and the internal model is the latter is actually implemented in a DBMS. Notice, that although not represented in the diagram, the check constraints, unique constraints, and default values all have all been implemented in the database schema just like they were in ...
Structured Query Language (SQL) Advanced Features
... calculation on the values in a set of selected rows Expression specified for AVG and SUM functions must result in a numeric value. The expression for Min, MAX, and COUNT can result in a numeric, date, or string value By default all values are included in the calculation regardless of whether they ar ...
... calculation on the values in a set of selected rows Expression specified for AVG and SUM functions must result in a numeric value. The expression for Min, MAX, and COUNT can result in a numeric, date, or string value By default all values are included in the calculation regardless of whether they ar ...
