This document provides an overview of MS SQL Server tips covering topics such as relationship databases, database design including normalization, indexes, and useful queries. Relationship databases organize information into tables that can be related through primary and foreign keys. Database design involves normalization to eliminate anomalies and improve performance. Indexes help optimize queries and common types include clustered, nonclustered, unique and full-text. Useful queries are provided to check index fragmentation and monitor currently running processes.

1. MS SQL SERVER TIPS
By Arman Aug-18

2. • Relationship Database Management System
• Database Design
• Indexes
• Useful Queries

3. RELATIONSHIP DATABASE MANAGEMENT SYSTEM
 Collection of information organized in tables
 Tables are also “Relations”
 Tables are constructed and associated to each other through shared fields.
 Fields are also “Columns” or “Attributes”
 A set of attributes comprises a record
 Records are also “Rows” or “Tuples”
 Tables are related through common fields designated as primary key and foreign keys.
 Allow us to find, update, and delete data quickly, and help to ensure accuracy

4. RELATIONSHIP DATABASE MANAGEMENT SYSTEM
 Primary Key :
 Primary key fields must be unique and cannot contain a null value
 Each table should have a primary key field[s].
 Composite Key: Using more than one field as a primary key.
 Foreign Key :
 Fields in a table that refer to the primary key in another table.
 The data in this field must exactly match data contained in the primary key

5. DATABASE DESIGN RELATIONSHIP TYPES
 One-to-one relationships
 One-to-many relationships
 Many-to-many relationships
 Mandatory or not?

6. DATABASE DESIGN NORMALIZATION
 First normal form (1NF)
 Second normal form (2NF)
 Third normal form (3NF)

7. DATABASE DESIGN NORMALIZATION 1NF
 First normal form (1NF)
I. It should only have single(atomic) valued attributes/columns.
II. Values stored in a column should be of the same domain
III. All the columns in a table should have unique names.
IV. And the order in which data is stored, does not matter.

8. DATABASE DESIGN NORMALIZATION 2NF
 Second normal form (2NF)
I. It should be in the First Normal form.
II. And, it should not have Partial Dependency.

9. DATABASE DESIGN NORMALIZATION 3NF
 Third normal form (3NF)
I. It is in the Second Normal form.
II. And, it doesn't have Transitive Dependency.

10. DATABASE DESIGN NORMALIZATION BCNF
 Boyce-Codd Normal Form (BCNF)
I. It should be in the Third Normal Form.
II. And, for any dependency A → B, A should be a super key.

11. DATABASE DESIGN NORMALIZATION 4NF
 Fourth Normal Form (4NF)

12. INDEXES TYPES
 Regulations
 1 Clustered Index per Table
 249 Non Clustered (2005)
 999 Non Clustered (2008+)
 16 Columns or 900 Bytes
 Clustered Index
 Nonclustered Index
 Unique index
 Filtered index
 Full-Text
 XML

13. CLUSTERED TABLE VS HEAP TABLE
Clustered Indexed Table Heap Table

14. CLUSTERED INDEX
 Clustered Index – sort order of the data within the table on the hard
drive and in memory.
 One per table
 Desired Qualities
 Narrow Data Type
 Unique
 Static
 Increasing

15. NONCLUSTERED INDEX
 Cover Common Queries
 Link to Clustered Indexes through Key
 Bookmark (Key/RID) Lookup

16. FRAGMENTATION
 Identifying Fragmentation
 2005
 DBCC SHOWCONTIG
 Above 2005
 sys.dm_db_index_physical_stats
Required Actions
avg_fragmentation_in_percent value Corrective statement
> 5% and < = 30% ALTER INDEX REORGANIZE
> 30% ALTER INDEX REBUILD WITH (ONLINE = ON)

17. USEFUL QUERIES
 Check index fragmentation using Transact-SQL
 2012
 2005
 DBCC SHOWCONTIG WITH TABLERESULTS, ALL_INDEXES;
 Currently running process
SELECT sqltext.TEXT,
req.session_id, req.status,req.command,
req.cpu_time, req.total_elapsed_time
,blocking_session_id ,wait_time ,wait_type
,logical_reads
FROM sys.dm_exec_requests req
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS
sqltext
SELECT a.index_id, name, avg_fragmentation_in_percent
FROM sys.dm_db_index_physical_stats (DB_ID(N'UniversoDB2018'),
OBJECT_ID(N'dbo.tblindividual'), NULL, NULL, NULL) AS a
JOIN sys.indexes AS b
ON a.object_id = b.object_id AND a.index_id = b.index_id;

18. USEFUL QUERIES
 Check index fragmentation using Transact-SQL
SELECT TOP 10 SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1,
((CASE qs.statement_end_offset
WHEN -1 THEN DATALENGTH(qt.TEXT)
ELSE qs.statement_end_offset
END - qs.statement_start_offset)/2)+1),
qs.execution_count,
qs.total_logical_reads, qs.last_logical_reads,
qs.total_logical_writes, qs.last_logical_writes,
qs.total_worker_time, qs.last_worker_time,
qs.total_elapsed_time/1000000 total_elapsed_time_in_S,
qs.last_elapsed_time/1000000 last_elapsed_time_in_S,
qs.last_execution_time, qp.query_plan
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp
ORDER BY qs.total_logical_reads DESC -- logical reads
-- ORDER BY qs.total_logical_writes DESC -- logical writes
-- ORDER BY qs.total_worker_time DESC -- CPU time

19. READ TYPES
 Index Scan
 Table Scan (Heap)
 Index Seek
 Key Lookup
 RID Lookup (heap)

20. RULES FOR EXECUTION PLAN COMPILATION
 Build up most resource efficient plan
 AS little page reads as possible
 Fastest Operation possible
 Choosing Indexes:
 Prefer read range over scan
 Prefer small indexes over large