REZA HESHAMI

DBA Developer

Responsibilities Designing Relational databases Developing interface layer

Environment Microsoft SQL Server, .NETSQL Layer: Stored procedures, functions ,CLR

ObjectsObject Layer: ADO. Net , Microsoft enterprise

library, Object-Relational mappers Query optimization/Performance tuning

Code review for performanceMissing indices

Applications

Single Sign on (SSO) Search Solutions

Search DatabaseSearch Engines

Import/Export solutionsSending to and receiving data from web servicesXML/CSV transformation

Frameworks Data warehouse and OLAP

Challenges

PerformanceMissing indexPoorly written queries Normalized vs. DenormalizedDeadlocks

Design Schema flexible to changesDDL (data definition language) Vs DML(data

manipulation language)○ example

Simple example Design a database to store user information

Username ,password, first name, last name, postal code

Requirement changes Email, Address, City, Province, Country, language and etc now is needed to be stored . Solution ?

CREATE TABLE Users( UserID INT NOT NULL Primary Key, UserName NVARCHAR(50) NOT NULL, FirstName NVARCHAR(50) NULL, LastName NVARCHAR(50) NULL, PostalCode NVARCHAR(50) NULL);

Simple example Option 1 add more column to the Users table Option 2 insert rows instead of columns

(How)

CREATE TABLE Users( UserID INT NOT NULL Primary Key, UserName NVARCHAR(50) NOT NULL );CREATE TABLE Properties( PropertyID INT NOT NULL Primary Key, PropertyName NVARCHAR(50) NOT NULL )CREATE TABLE UserProperty( PropertyID INT NOT NULL Primary Key, UserID INT NOT NULL , value NVARCHAR(100) NOT NULL )

Many to Many Relation

XML DataType –Hybrid design

CREATE TABLE Users( UserID INT NOT NULL Primary Key, UserName NVARCHAR(50) NOT NULL , UserProperty XML);CREATE TABLE Properties( PropertyID INT NOT NULL Primary Key, PropertyName NVARCHAR(50) NOT NULL )CREATE TABLE UserProperty( PropertyID INT NOT NULL Primary Key, UserID INT NOT NULL , value NVARCHAR(100) NOT NULL )

XML DataType –Hybrid design XML Advantages

FlexibilityEasy to parse and to serialized in to objects

DisadvantagesSearching trough XML is SlowMaintenance – adds over head to insert and

update XML model is not a replacement for

Relational model

Good to know about

Paging in SQL Trees & Hierarchies in SQL Graph in SQL Recursive query in SQL (using Common

Table Expressions) XML manipulation (XPATH,XQUERY) CLR objects in MS SQL Server