Chapter 1: SQL Server 2012 Database Design 1/23/2022 1 Module Overview • • • • • 1/23/2022 Data Modeling Database Creation using GUI Database Creation using T-SQL Scripts File locations and Size Parameters DB Log Files, Growth, and Placement 2 Data Modeling • The whole process of Data Modeling is called Data Normalization or Database Normalization. • Normalization is a process of reducing redundant/duplicate data. It means that we have some data element in a row/record that we may not need in that same table. So, it is a rule of thumb that anytime we find a duplicate data element in a record, we may need to create another table with all the duplicates. • Again, Normalization is the process of organizing data in the most optimized way for better performance and to avoid unnecessary redundant data in a database. This includes creating tables and establishing relationships between tables to eliminate redundancy and inconsistent data. 1/23/2022 3 Data Modeling Advantages of Data Normalization: • Minimizes the amount of space required to store the data by eliminating redundant data minimizes the risk of data inconsistencies within a database • Minimizes the introduction of possible updates and delete anomalies • Maximizes the stability of the data structure • Eliminates duplicate/redundant data from tables 1/23/2022 4 Data Modeling • Reduce the chances of data anomaly/inconsistency that occur in a database Provides efficient management of data and space (HD) Fewer chances of making mistakes in editing data • Effective usage of storage • Writing/inserting and Data update is faster 1/23/2022 5 Data Modeling Disadvantage of normalization: • Data Read/Retrieval is slower • Requires writing more complicated script/queries to retrieve data 1/23/2022 6 Data Modeling Types of Normalization/Normalization forms: • There are different normalization forms. • However, OLTP and OLAP databases for commercial purposes, Data Modeling use only first 3 normalization forms. The other normalization forms are used for academic and research purposes only. • The normalization forms are 1NF, 2NF, 3NF, 4NF, 5NF, 6NF etc. • Among all these normalization forms, only 1NF, 2NF, and 3NF normalization forms are used for data normalization and commercial databases. • Edgar F. Codd is the inventor of relational model as he first defined the relational model of databases. Codd defined First, second, and third normal form or 1NF, 2NF and 3NF respectively. 1/23/2022 7 Data Modeling • In some schemes/systems/designs such as data warehousing, you keep your design deformalized for performance reasons and primarily because you are typically not updating the data in a data warehouse. Denormalization: • Denormalization is the reverse process of normalization. In Denormalization, we accept data redundancy in a table. • De-normalization is a logical database design method to merge data from multiple related tables into one table. The characteristic of a De-normalization database is that it has wide tables with more columns per table. • It helps to improve the performance of a query. It is because it requires reading related data from a few tables. So, some calculated values can be kept in the column of a table. In a way, it reduces the overhead of doing calculations with every query. 1/23/2022 8 Data Modeling Why Denormalize a Database: • The only reason to Denormalization a database is to increase performance. • For example, in an OLAP (On-Line Analytical Processing) application, you could Denormalize the database for creating reports that are used frequently, such as reports that include summarized numbers for quarterly profit. Instead of calculating these values each time you need them, you can use the existing records to be queried again without calculation. This type of denormalization works best when the data is frequently changed, in the case of historical data. 1/23/2022 9 Normalization Form Example Un-normalized Students table: Student# AdvID AdvName AdvRoom Class1 Class2 123 123A James 555 102-8 104-9 124 123B Smith 467 209-0 102-8 1/23/2022 10 Normalization Rules Rule 1: • In the First Normal Form (1NF), every entity has a primary key attribute. Each attribute must have only one value, and not a set of values. • In simple word: • Eliminate Repeating Groups or Remove duplicate data/similar data from the same row of a table and store the repeating records in another table. Use a key to relate the records between the tables created. • For a database to be in 1NF, it must not have any repeating groups. For a single instance, data in the repeating group may have multiple values for a given attribute. 1/23/2022 11 1st Normal Form Example Un-normalized Students table: Student# AdvID AdvName AdvRoom Class1 Class2 123 123A James 555 102-8 104-9 124 123B Smith 467 209-0 102-8 Normalized Students table: Student# AdvID AdvName AdvRoom Class# 1/23/2022 123 123 124 124 123A 123A 123B 123B James James Smith Smith 555 555 467 467 102-8 104-9 209-0 102-8 12 Normalization Rules Second Normal Form (2NF): • Tables to be in 2NF, it must satisfy 1NF and all non-key attributes must fully depend on the primary key. Reduce data redundancy by extracting redundant data and moving it a new table. • All requirements for 1st NF must be met. • Redundant data across multiple rows of a table must be moved to a separate table. • The resulting tables must be related to each other by use of foreign key. • Eliminate/Remove Duplicate/Redundant data that is in same column on multiple rows and store these records in a new table. 1/23/2022 ACT American College of Technology 13 2nd Normal Form Example Students table Student# AdvID 123 123A 124 123B AdvName James Smith AdvRoom 555 467 Registration table 1/23/2022 Student# 123 123 124 124 Class# 102-8 104-9 209-0 102-8 Class# 102-8 104-9 209-0 14 Normalization Rules Third Normal Form (3NF): • A table to be in 3NF, it must satisfy the 1NF, 2NF and require to remove all non-key attributes relying on another non-key attribute that relies on the primary key. • Eliminate Columns/Non key attributes dependent on another non key attribute. So, Non key Attributes cannot depend on another non key attribute. Each non-key attribute must depend on a primary key (exactly like 2NF). • Eliminate fields that do not depend on the primary key. • That is, any field that is dependent not only on the primary key but also on another field must be moved to another table. 1/23/2022 ACT American College of Technology 15 3rd Normal Form Example Students table: Student# AdvID 123 123A 124 123B Student table: 1/23/2022 AdvName AdvRoom James 555 Smith 467 Advisor table: Student# AdvID AdvID AdvName AdvRoom 123 123A 123A James 555 124 123B 123B Smith 467 16 Normal Form Example Cont. Students table: Student# AdvID 123 123A 124 123B Advisor table: Registration table: Student# 123 123 124 124 Class# 102-8 104-9 209-0 102-8 Class table: Class# 102-8 104-9 209-0 AdvID AdvName AdvRoom 123A James 555 123B Smith 467 1/23/2022 17 ER Diagram • E-R diagram stands for Entity Relationship Diagram. • An Entity Relationship Diagram (ERD) is a way to graphically describe the relationship between data in a table. This relationship is established by using same value of two columns of two tables. • Relationships describe the connection between two Entities/Tables. There are different types of relationship. For example, a relationship could be one-to-one, one-to-many, and many-to-many. • A relationship works by matching data in key columns. A good practice is to use the same name for connected columns of the tables. 1/23/2022 18 ER-Diagram • E-R Diagram helps to organize data into entities of a system of any project. It also helps to define relationship between the entities/tables. • E-R Diagram helps Data Analyst/Modeler to produce a good database structure so that the data can be stored and retrieved most efficiently. • Again, an E-R diagram is a specialized graphical representation of relationship between entities in a database. • E-R diagram is a diagram that is used in data modeling for Relational Databases. It shows the structure of each table including column name, data type, length, constraints, Primary Key and links between entities. 1/23/2022 19 ER-Diagram for Student Advisory Database 1/23/2022 20 Data Dictionary For Student Advisory Database 1/23/2022 21 Database Creation using GUI(Student Advisory DB) Connect to Database Server With SSMS 1/23/2022 22 Database Creation using GUI(Student Advisory DB) Right Click on the Database Node and Click on New Database 1/23/2022 23 Database Creation using GUI(Student Advisory DB) Provide “Student Advisory” on the Database Name 1/23/2022 24 Database Creation using GUI(Student Advisory DB) Review the Option for the Database 1/23/2022 25 Database Creation using GUI(Student Advisory DB) Review the Filegroup for the Database and the Click Ok 1/23/2022 26 Database Creation using GUI(Student Advisory DB) Confirm the “Student Advisory” Database is created 1/23/2022 27 Database Creation using T-SQL Scripts (Student Advisory DB) Click “New Query” from the menu 1/23/2022 28 Database Creation using T-SQL Scripts (Student Advisory DB) Write the below create script to create the “Student Advisory” with Script 1/23/2022 29 Database Creation using T-SQL Scripts Genrate (Student Advisory DB-Copy) 1/23/2022 30 Database Creation using T-SQL Scripts Genrate (Student Advisory DB-Copy) 1/23/2022 31 Database Properties (General) 1/23/2022 32 Database Properties (Files) 1/23/2022 33 Database Properties (Filegroup) 1/23/2022 34 Database Properties (Options) 1/23/2022 35 Database Properties (Change Tracking) 1/23/2022 36 Database Properties (Permissions) 1/23/2022 37 Student Advisory Database Tables Defintion Scripts 1/23/2022 38 Database ER-Diagram Generated from DB 1/23/2022 39
