No Slide Title
... Let E1 and E2 be relational-algebra expressions; the following are all relational-algebra expressions: E1 E2 E1 - E2 E1 x E2 p (E1), P is a predicate on attributes in E1 s(E1), S is a list consisting of some of the attributes in E1 x (E1), x is the new name for the result of E1 D ...
... Let E1 and E2 be relational-algebra expressions; the following are all relational-algebra expressions: E1 E2 E1 - E2 E1 x E2 p (E1), P is a predicate on attributes in E1 s(E1), S is a list consisting of some of the attributes in E1 x (E1), x is the new name for the result of E1 D ...
Database Compiler Concepts - University of Connecticut
... SQL has the SELECT Statement for Retrieving Info. from a Database (Not Relational Algebra Select) SQL vs. Formal Relational Model SQL Allows a Table (Relation) to have Two or More Identical Tuples in All Their Attribute Values Hence, an SQL Table is a Multi-set (Sometimes Called a Bag) of Tuples ...
... SQL has the SELECT Statement for Retrieving Info. from a Database (Not Relational Algebra Select) SQL vs. Formal Relational Model SQL Allows a Table (Relation) to have Two or More Identical Tuples in All Their Attribute Values Hence, an SQL Table is a Multi-set (Sometimes Called a Bag) of Tuples ...
Session 5
... What is an INDEX by the way? Index is a general term for an Oracle/SQL feature, used primarily to speed execution and (sometimes) impose uniqueness upon certain data. Indexes provide a faster access method to one table’s data than doing a ‘full table scan’. So instead of a query having to search all ...
... What is an INDEX by the way? Index is a general term for an Oracle/SQL feature, used primarily to speed execution and (sometimes) impose uniqueness upon certain data. Indexes provide a faster access method to one table’s data than doing a ‘full table scan’. So instead of a query having to search all ...
PPT
... both the Fall 2009 semester and in the Spring 2010 semester” select course_id from section as S where semester = ’Fall’ and year = 2009 and exists (select * from section as T where semester = ’Spring’ and year= 2010 and S.course_id = T.course_id); ...
... both the Fall 2009 semester and in the Spring 2010 semester” select course_id from section as S where semester = ’Fall’ and year = 2009 and exists (select * from section as T where semester = ’Spring’ and year= 2010 and S.course_id = T.course_id); ...
Tutorial on basic MIST SQL language use
... simple, like with all languages, either human or computer, the combination of the words in the language can create very complex patterns and requests. So it is with SQL. This document is not intended to teach all the ways the SQL language can be combined, nor is it a comprehensive list of all langua ...
... simple, like with all languages, either human or computer, the combination of the words in the language can create very complex patterns and requests. So it is with SQL. This document is not intended to teach all the ways the SQL language can be combined, nor is it a comprehensive list of all langua ...
SQL – Part II
... Figure 7-1 Pine Valley Furniture Company Customer_T and Order_T tables with pointers from customers to their orders ...
... Figure 7-1 Pine Valley Furniture Company Customer_T and Order_T tables with pointers from customers to their orders ...
Document
... As a running example, we exhibit in Figure 1 a snowflake schema for a data warehouse for keeping track of students’ attendance in a college. The fact table of this schema is ATTENDANCE, and its dimension tables are DATE, ROOM, LECTURER, STUDENT and COURSE; HOLIDAY is a subdimension of DATE, and DEPA ...
... As a running example, we exhibit in Figure 1 a snowflake schema for a data warehouse for keeping track of students’ attendance in a college. The fact table of this schema is ATTENDANCE, and its dimension tables are DATE, ROOM, LECTURER, STUDENT and COURSE; HOLIDAY is a subdimension of DATE, and DEPA ...
A, F - COW :: Ceng
... Example (con’t) Given: R2 = (ABCFGH; {ABHC, BGHF, FAH, BHG}) step 1: Find a FD that violates BCNF. Not ABH C or BGH F, since BH is a key of R2 F AH violates BCNF since F is not a superkey (F+ =AH) step 2: Split R2 into: R21 = (FAH, {F AH}) R22 = (BCFG; {}) Note 1: Both R21 and R22 are in ...
... Example (con’t) Given: R2 = (ABCFGH; {ABHC, BGHF, FAH, BHG}) step 1: Find a FD that violates BCNF. Not ABH C or BGH F, since BH is a key of R2 F AH violates BCNF since F is not a superkey (F+ =AH) step 2: Split R2 into: R21 = (FAH, {F AH}) R22 = (BCFG; {}) Note 1: Both R21 and R22 are in ...
JAVA DATABASE CONNECTIVITY (JDBC)
... A relational database is a logical representation of data that allows the data to be accessed without consideration of its physical structure. A relational database stores data in tables. ...
... A relational database is a logical representation of data that allows the data to be accessed without consideration of its physical structure. A relational database stores data in tables. ...
Query Answering Under Exact View Assumption in Local As View
... If m < n, then for each i ∈ {n − m, ..., n}, create a new variable xi , and for each tuple haxbi unifiable with view, create a new tuple haxi bi. Disjoint all tuples for a variable xi by disjoint condition. Then apply π-step as for m = n. In case when the projection is the multicolumn projection v = ...
... If m < n, then for each i ∈ {n − m, ..., n}, create a new variable xi , and for each tuple haxbi unifiable with view, create a new tuple haxi bi. Disjoint all tuples for a variable xi by disjoint condition. Then apply π-step as for m = n. In case when the projection is the multicolumn projection v = ...
20060607_paul
... We are testing Qstore on the current Lung dataset for feedbacks and fine-tuning. ...
... We are testing Qstore on the current Lung dataset for feedbacks and fine-tuning. ...
Chapter 5 review
... (1,0):(0,1): Foreign key goes on whichever side will cause fewer nulls (1,1):(1,1): This relationship almost never exists in the real world. You probably made a mistake. Verify your cardinalities, or merge the two tables. Exception: this relationship is sometimes used for database performance ...
... (1,0):(0,1): Foreign key goes on whichever side will cause fewer nulls (1,1):(1,1): This relationship almost never exists in the real world. You probably made a mistake. Verify your cardinalities, or merge the two tables. Exception: this relationship is sometimes used for database performance ...
First normal form
... A table that lacks a unique key. Such a table would be able to accommodate duplicate rows, in violation of condition 3. A view whose definition mandates that results be returned in a particular order, so that the row-ordering is an intrinsic and meaningful aspect of the view.[5] This violates condit ...
... A table that lacks a unique key. Such a table would be able to accommodate duplicate rows, in violation of condition 3. A view whose definition mandates that results be returned in a particular order, so that the row-ordering is an intrinsic and meaningful aspect of the view.[5] This violates condit ...
PPTX
... So far, we have implicitly assumed that there is only one DB user who executes one SQL statement at a time. In reality, a DBS may have many concurrent users. Each user may issue a sequence of SQL statements that form a logical unit (transaction). The DBS is in charge of ordering the SQL statements f ...
... So far, we have implicitly assumed that there is only one DB user who executes one SQL statement at a time. In reality, a DBS may have many concurrent users. Each user may issue a sequence of SQL statements that form a logical unit (transaction). The DBS is in charge of ordering the SQL statements f ...
week11 - Arms-A
... Costs associated with the three actions, as a function of which indexes are selected (Ref. Fig. 6.17 2nd ed.) Star index is an index on StarName, Movie index is an index on MovieTitle and movieYear. The numbers in rows 2-5 of the table are no. of disk accesses for the action. ...
... Costs associated with the three actions, as a function of which indexes are selected (Ref. Fig. 6.17 2nd ed.) Star index is an index on StarName, Movie index is an index on MovieTitle and movieYear. The numbers in rows 2-5 of the table are no. of disk accesses for the action. ...
Part 4: The Relational Model
... • The SQL-92 standard contains domain definitions, but until now few systems support them. Oracle 8i, IBM DB2 V5, and MS SQL Server 7 all do not support CREATE DOMAIN. But e.g. user-defined data types in SQL Server ...
... • The SQL-92 standard contains domain definitions, but until now few systems support them. Oracle 8i, IBM DB2 V5, and MS SQL Server 7 all do not support CREATE DOMAIN. But e.g. user-defined data types in SQL Server ...
R - Department of Computer Science
... Let r and s be relations on schemas R and S respectively.The result is a relation on schema R S which is obtained by considering each pair of tuples tr from r and ts from s. If tr and ts have the same value on each of the attributes in R S, a tuple t is added to the result, where t has the ...
... Let r and s be relations on schemas R and S respectively.The result is a relation on schema R S which is obtained by considering each pair of tuples tr from r and ts from s. If tr and ts have the same value on each of the attributes in R S, a tuple t is added to the result, where t has the ...
Chapter 8 - Spatial Database Group
... Rule 7: Stable columns with few values are good candidates for bitmap indexes if the columns appear in WHERE conditions. Rule 8: Avoid indexes on combinations of columns. Most optimization components can use multiple indexes on the same table. ...
... Rule 7: Stable columns with few values are good candidates for bitmap indexes if the columns appear in WHERE conditions. Rule 8: Avoid indexes on combinations of columns. Most optimization components can use multiple indexes on the same table. ...
Introduction to XML
... insert – returns _id of new record or –1 if error occurred update – returns number of rows affected delete – number of rows affected (0 if no where clause) » pass ‘1’ as where clause to get count in this case ...
... insert – returns _id of new record or –1 if error occurred update – returns number of rows affected delete – number of rows affected (0 if no where clause) » pass ‘1’ as where clause to get count in this case ...
Database-lecture 10
... In this example: the sub query is used in the having clause The example goal: to retrieve the number of projects for each employee who works on at least one project in the works_on table. ...
... In this example: the sub query is used in the having clause The example goal: to retrieve the number of projects for each employee who works on at least one project in the works_on table. ...
New Database Design for the APS Survey and Alignment Data
... forms are basically restrictions on a relational database schema that prevent redundancy as well as anomalies in the database. If a relation is in one of these normal forms, we know that certain types of problems cannot happen. We also know whether we have a well-designed relational schema or whethe ...
... forms are basically restrictions on a relational database schema that prevent redundancy as well as anomalies in the database. If a relation is in one of these normal forms, we know that certain types of problems cannot happen. We also know whether we have a well-designed relational schema or whethe ...
Universal Modeling Language (UML) Class Diagrams Compared to
... Bindings to object-oriented programming languages ...
... Bindings to object-oriented programming languages ...
Relationalizing RDF stores for tools reusability
... that obtained using an RDF visualization tool called GRUFF [4] using a variety of queries of varying complexity. R2D queries were fired against Jena’s in-memory data store. Table 1 lists the results obtained for an RDF triples database size of 0.5M. ...
... that obtained using an RDF visualization tool called GRUFF [4] using a variety of queries of varying complexity. R2D queries were fired against Jena’s in-memory data store. Table 1 lists the results obtained for an RDF triples database size of 0.5M. ...
DB Tables and Relationships
... Survey data into two relations (tables) …so now we need to create a table for the rest of the data Don’t forget that each record must have a unique house identifier …and what we will use this for? ...
... Survey data into two relations (tables) …so now we need to create a table for the rest of the data Don’t forget that each record must have a unique house identifier …and what we will use this for? ...