Discussion about normal forms in SQL

[chowdary10]

[quote author=galigannarao link=topic=219396.msg2703251#msg2703251 date=1312304553]
bommalu esta chusko explain chese time ledu ippudu
logical model
[img]http://www.1keydata.com/datawarehousing/logical-data-model.jpg[/img]
Physical model
[img width=440 height=370]http://www.1keydata.com/datawarehousing/physical-data-model.jpg[/img]
[/quote]

assalu ee renditiki theda emi vundi, just data types define cheyatam thappa emi ledu kada theda

[galigannarao]

[quote author=KINDAL link=topic=219396.msg2703339#msg2703339 date=1312305361]
assalu ee renditiki theda emi vundi, just data types define cheyatam thappa emi ledu kada theda
[/quote]
Logical Data Model:
A logical data model describes the data in as much detail as possible, without regard to how they will be physical implemented in the database. Features of a logical data model include:

    Includes all entities and relationships among them.
    All attributes for each entity are specified.
    The primary key for each entity is specified.
    Foreign keys (keys identifying the relationship between different entities) are specified.
    Normalization occurs at this level.

The steps for designing the logical data model are as follows:

    Specify primary keys for all entities.
    Find the relationships between different entities.
    Find all attributes for each entity.
    Resolve many-to-many relationships.
    Normalization.

Physical Data Model
Physical data model represents how the model will be built in the database. A physical database model shows all table structures, including column name, column data type, column constraints, primary key, foreign key, and relationships between tables. Features of a physical data model include:

    Specification all tables and columns.
    Foreign keys are used to identify relationships between tables.
    Denormalization may occur based on user requirements.
    Physical considerations may cause the physical data model to be quite different from the logical data model.
    Physical data model will be different for different RDBMS. For example, data type for a column may be different between MySQL and SQL Server.

The steps for physical data model design are as follows:

    Convert entities into tables.
    Convert relationships into foreign keys.
    Convert attributes into columns.
    Modify the physical data model based on physical constraints / requirements.

[manoghna]

[quote author=KINDAL link=topic=219396.msg2703339#msg2703339 date=1312305361]
assalu ee renditiki theda emi vundi, just data types define cheyatam thappa emi ledu kada theda
[/quote]Logical datamodel : it contains the logic of the database as the name it self says... it is creating a rough map of the database,
oka databse create cheyali ante andhulo asalu emi entities store cheyali,a entities lo ye attributes undali, and a entities madhya primarykey,foreign key create cheyali


Physical datamodel : Now based on the logical we have to create the physical datamodel(tables and cloumsn in it) with appropriate datatypes and relations - this is the final step before creating the database.

[chowdary10]

[quote author=meghana9 link=topic=219396.msg2703371#msg2703371 date=1312305731]
Logical datamodel : it contains the logic of the database as the name it self says... it is creating a rough map of the database,
oka databse create cheyali ante andhulo asalu emi entities store cheyali,a entities lo ye attributes undali, and a entities madhya primarykey,foreign key create cheyali


Physical datamodel : Now based on the logical we have to create the physical datamodel(tables and cloumsn in it) with appropriate datatypes and relations - this is the final step before creating the database.
[/quote]

thankyou naaku ide artham ayyendi  ~"!

[Herndon- VA]

[quote author=meghana9 link=topic=219396.msg2702903#msg2702903 date=1312300395]
After 2nd normal form you have to look ,if they are any dependencies in the same table, for example : if the table contains
emp name,city and zipcode in the 2nd normal form... city is dependent on zipcode kada.. so avi rendu same table lo undakudadhu you have to create [b][size=14pt]separates tables with emp name and city as columns in one table and emp name and zipcode[/size][/b] as columns in another table... now e two tables ki primary and foriegn key relationship create cheyali...
ila konni tables ki relation lekunda vuntayi vatini remove cheyali.. ade 3rd normal form ante...

In brief: 2nd normal ni inka separate cheyali more tables ga ,and primary,foriegn key relationship leni tables ni remove cheyali
[/quote]

Adi correct aa  @$MN @$MN @$MN @$MN

3rd normal form la, Emp Name and City Foriegn key oka table,
2nd table with City Primary Key, City name, ZipCode.  sCo_^Y sCo_^Y sCo_^Y sCo_^Y
Okka city ki multiple zipcode lu unte, move Zipcode to another table. and it will be in between emp table and city table...  sCo_^Y sCo_^Y sCo_^Y CITI#H@ CITI#H@ CITI#H@

[manoghna]

[quote author=subba rao link=topic=219396.msg2703401#msg2703401 date=1312306074]
Adi correct aa  @$MN @$MN @$MN @$MN

3rd normal form la, Emp Name and City Foriegn key oka table,
2nd table with City Primary Key, City name, ZipCode.  sCo_^Y sCo_^Y sCo_^Y sCo_^Y
Okka city ki multiple zipcode lu unte, move Zipcode to another table. and it will be in between emp table and city table...  sCo_^Y sCo_^Y sCo_^Y CITI#H@ CITI#H@ CITI#H@
[/quote]different cities ki same zipcode vuntundhi kabate..adhi vere table ki move cheyali... same table lo vunte duplicate values may occur

[manoghna]

[quote author=subba rao link=topic=219396.msg2703401#msg2703401 date=1312306074]
Adi correct aa  @$MN @$MN @$MN @$MN

3rd normal form la, Emp Name and City Foriegn key oka table,
2nd table with City Primary Key, City name, ZipCode.  sCo_^Y sCo_^Y sCo_^Y sCo_^Y
Okka city ki multiple zipcode lu unte, move Zipcode to another table. and it will be in between emp table and city table...  sCo_^Y sCo_^Y sCo_^Y CITI#H@ CITI#H@ CITI#H@
[/quote]nenu general ga chepanu... city ye primary key ga vundali or foreign key ga vundlai ani chepaledhu.... empid(primary key) ,emp name,city will be one table...
2nd table  identity coumn(primary key),empid(foriegn key),emp name,zipcode

sCo_^Y did I answered your question

[Herndon- VA]

[quote author=meghana9 link=topic=219396.msg2703411#msg2703411 date=1312306177]
different cities ki same zipcode vuntundhi kabate..adhi vere table ki move cheyali... same table lo vunte duplicate values may occur
[/quote]

Different cities ki same Zipcode untadi anna assumption la,

ZipCode ---< City ---< Emp

ZipCode la Zip Code and Z1

City la City, C1 and Z1

Emp la Emp Details and C1

Total 3 tables kada.... Emp_name vere tebles la repeat kaavoddu kada according to 3rd normal form.
Paina nee statement correct aa, idi correct anna confusion la unna. Inka oka 5 members nee statements ki Rock annaru.
Please clarify.

[The QUEEN]

sSa_j@il sSa_j@il sSa_j@il

[galigannarao]

[quote author=The QUEEN link=topic=219396.msg2703463#msg2703463 date=1312306558]
sSa_j@il sSa_j@il sSa_j@il
[/quote] Ammugif Ammugif Ammugif dont spam here

[Herndon- VA]

[quote author=meghana9 link=topic=219396.msg2703442#msg2703442 date=1312306446]
nenu general ga chepanu... city ye primary key ga vundali or foreign key ga vundlai ani chepaledhu.... empid(primary key) ,emp name,city will be one table...
2nd table  identity coumn(primary key),empid(foriegn key),emp name,zipcode

sCo_^Y did I answered your question
[/quote]

Nenu cheppina form em number normalised form? I always thought names should not repeated. It should only be keys and tables should be in a hierarchy.

[Herndon- VA]

[quote author=galigannarao link=topic=219396.msg2703468#msg2703468 date=1312306612]
Ammugif Ammugif Ammugif dont spam here
[/quote]

CITI#H@ CITI#H@

Naa pina question

[manoghna]

[quote author=subba rao link=topic=219396.msg2703449#msg2703449 date=1312306492]
Different cities ki same Zipcode untadi anna assumption la,

ZipCode ---< City ---< Emp

ZipCode la Zip Code and Z1

City la City, C1 and Z1

Emp la Emp Details and C1

Total 3 tables kada.... Emp_name vere tebles la repeat kaavoddu kada according to 3rd normal form.
Paina nee statement correct aa, idi correct anna confusion la unna. Inka oka 5 members nee statements ki Rock annaru.
Please clarify.
[/quote]Citi oka table lo vundhi,ZIpcode inko table lo vundhi and those table have primary,foriegn key relation  sCo_^Y

[quote author=subba rao link=topic=219396.msg2703471#msg2703471 date=1312306626]
Nenu cheppina form em number normalised form? I always thought names should not repeated. It should only be keys and tables should be in a hierarchy.
[/quote]nenu chepina example lo names ekada repeat avuthayi... duplicates vundavu kada 

[Herndon- VA]

[quote author=meghana9 link=topic=219396.msg2703487#msg2703487 date=1312306755]
Citi oka table lo vundhi,ZIpcode inko table lo vundhi and those table have primary,foriegn key relation  sCo_^Y
nenu chepina example lo names ekada repeat avuthayi... duplicates vundavu kada 
[/quote]

+_( +_( +_(

Naaku telishi nenu cheppindi correct 3rd normalised form.

Let us ask some one else...


[quote author=meghana9 link=topic=219396.msg2703442#msg2703442 date=1312306446]
nenu general ga chepanu... city ye primary key ga vundali or foreign key ga vundlai ani chepaledhu.... [b]empid(primary key) ,emp name[/b],city will be one table...
2nd table  identity coumn(primary key),[b]empid(foriegn key),emp name[/b],zipcode

sCo_^Y did I answered your question
[/quote]

[manoghna]

[quote author=subba rao link=topic=219396.msg2703529#msg2703529 date=1312307222]
+_( +_( +_(

Naaku telishi nenu cheppindi correct 3rd normalised form.

Let us ask some one else...
[/quote]ok sare...
miru chepindhi denormalised form ani anukuntuna nenu ...