Candidate and Primary Keys

فهرست عناوین اصلی در این پاورپوینت

فهرست عناوین اصلی در این پاورپوینت

● David M. Kroenke’s
● Chapter Premise
● How Many Tables?
● But first –
● The Relational Model
● Important Relational Model Terms
● Entity
● Relation
● A Relation
● A Relation with Values
of Varying Length
● Tables That Are Not Relations:
Multiple Entries per Cell
● Tables That Are Not Relations:
Table with Required Row Order
● Alternative Terminology
● Functional Dependency
● Functional Dependencies Are Not Equations
● Composite Determinants
● Functional Dependency Rules
● Functional Dependencies in the SKU_DATA Table
● Functional Dependencies in the ORDER_ITEM Table
● What Makes Determinant Values Unique?
● Keys
● Candidate and Primary Keys
● Surrogate Keys
● Foreign Keys
● The Referential Integrity Constraint
● Foreign Key with a
Referential Integrity Constraint
● Modification Anomalies
● Normal Forms
● Eliminating Modification Anomalies from Functional Dependencies in Relations
● Putting a Relation into BCNF:
EQUIPMENT_REPAIR
● Putting a Relation into BCNF:
New Relations
● Putting a Relation into BCNF:
SKU_DATA
● Putting a Relation into BCNF:
New Relations
● Multivaled Dependencies
● Eliminating Anomolies from Multivaled Dependencies
● David M. Kroenke’s
Database Processing
Fundamentals, Design, and Implementation
(10th Edition)

نوع زبان: انگلیسی حجم: 8.11 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 45 صفحه
سطح مطلب: نامشخص پسوند فایل: ppt
گروه موضوعی: زمان استخراج مطلب: 2019/05/17 08:42:12

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عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

key, relation, table, primary, dependency, functional, sku, column, foreign, value, determinant, datum,

توجه: این مطلب در تاریخ 2019/05/17 08:42:12 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

http://cs.sru.edu/~whit/cpsc323/SlidesKroenke10/kroenke10_ch03.ppt

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عبارات پرتکرار و مهم در این اسلاید عبارتند از: key, relation, table, primary, dependency, functional, sku, column, foreign, value, determinant, datum,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

david m. kroenke’s chapter three the relational model and normalization database processing fundamentals design and implementation chapter premise we have received one or more tables of existing data the data is to be stored in a new database question should the data be stored as received or should it be transformed for storage how many tables should we store these two tables as they are or should we combine them into one table in our new database ۱.bin but first we need to understand the relational model relational model terminology the relational model introduced in ۱۹۷ created by e.f. codd he was an ibm engineer the model used mathematics known as relational algebra now the standard model for commercial dbms products important relational model terms entity relation functional dependency determinant candidate key composite key primary key surrogate key foreign key referential integrity constraint normal form multivalued dependency entity an entity is some identifiable thing that users want to track customers computers sales relation relational dbms products store data about entities in relations which are a special type of table a relation is a two dimensional table that has the following characteristics rows contain data about an entity columns contain data about attributes of the entity all entries in a column are of the same kind each column has a unique name cells of the table hold a single value the order of the columns is unimportant the order of the rows is unimportant no two rows may be identical a relation ۴.bin a relation with values of varying length ۵.bin tables that are not relations multiple entries per cell ۲.bin tables that are not relations table with required row order ۳.bin alternative terminology although not all tables are relations the terms table and relation are normally used interchangeably the following sets of terms are equivalent ۶.bin functional dependency a functional dependency occurs when the value of one a set of attribute s determines the value of a second set of attribute s studentid  studentname studentid  dormname dormroom fee the attribute on the left side of the functional dependency is called the determinant functional dependencies may be based on equations extendedprice quantity x unitprice quantity unitprice  extendedprice function dependencies are not equations functional dependencies are not equations objectcolor  weight objectcolor  shape objectcolor  weight shape composite determinants composite determinant a determinant of a functional dependency that consists of more than one attribute studentname classname  grade functional dependency rules if a  b c then a  b and a c if a b  c then neither a nor b determines c by itself functional dependencies in the sku data table functional dependencies in the sku data table sku  sku description department buyer sku description  sku department buyer buyer  department functional dependencies in the order item table functional dependencies in the order item table ordernumber sku  quantity price extendedprice quantity price  extendedprice what makes determinant values unique a determinant is unique in a relation if and only if it determines every other column in the relation you cannot find the determinants of all functional dependencies simply by looking for unique values in one column data set limitations must be logically a determinant keys a key is a combination of one or more columns that is used to identify rows in a relation a composite key is a key that consists of two or more columns candidate and primary keys a candidate key is a key that determines all of the other columns in a relation a primary key is a candidate key selected as the primary means of identifying rows in a relation there is one and only one primary key per relation the primary key may be a composite key the ideal primary key is short numeric and never changes surrogate keys a surrogate key as an artificial column added to a relation to serve as a primary key dbms supplied short numeric and never changes – an ideal primary key has artificial values that are meaningless to users normally hidden in forms and reports surrogate keys note the primary key of the relation is underlined below rental property without surrogate key rental property street city state province zip postalcode country rental rate rental property with surrogate key rental property propertyid street city state province zip postalcode country rental rate foreign keys a foreign key is the primary key of one relation that is placed in another relation to form a link between the relations a foreign key can be a single column or a composite key the term refers to the fact that key values are foreign to the relation in which they appear as foreign key values foreign keys note the primary keys of the relations are underlined and any foreign keys are in italics in the relations below department departmentname budgetcode managername employee employeenumber employeename departmentname the referential integrity constraint a referential integrity constraint is a statement that limits the values of the foreign key to those already existing as primary key values in the corresponding relation foreign key with a referential integrity constraint note the primary key of the relation is underlined and any foreign keys are in italics in the relations below sku data sku sku description department buyer order item ordernumber sku quantity price extendedprice where order item.sku must exist in sku data.sku modification anomalies deletion anomaly insertion anomaly update anomaly modification anomalies the equipment repair table before and after an incorrect update operation on acquisitioncost for type drill press ۱۳.bin ۱۴.bin normal forms relations are categorized as a normal form based on which modification anomalies or other problems that they are subject to ۱۵.bin normal forms ۱nf – a table that qualifies as a relation is in ۱nf ۲nf – a relation is in ۲nf if all of its nonkey attributes are dependent on all of the primary key ۳nf – a relation is in ۳nf if it is in ۲nf and has no determinants except the primary key boyce codd normal form bcnf – a relation is in bcnf if every determinant is a candidate key i swear to construct my tables so …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: key, relation, table, primary, dependency, functional, sku, column, foreign, value, determinant, datum,

این فایل پاورپوینت شامل 45 اسلاید و به زبان انگلیسی و حجم آن 8.11 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/05/17 08:42:12 استخراج شده است.

http://cs.sru.edu/~whit/cpsc323/SlidesKroenke10/kroenke10_ch03.ppt

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