Upload
griffin-griffin
View
232
Download
0
Embed Size (px)
Citation preview
Introduction
• MS SQL Server is a database server • Product of Microsoft• Enables user to write queries and other
SQL statements and execute them• Consists of several features. A few are:
– Query Analyzer– Profiler– Service Manager– Bulk Copy Program (BCP)
Profiler
• Monitoring tool
• Used for performance tuning
• Uses traces – an event monitoring protocol
• Event may be a query or a transaction like logins etc
Service Manager
• Helps us to manage services
• More than one instance of SQL server can be installed in a machine
• First Instance is called as default instance
• Rest of the instances (16 max) are called as named instances
• Service manager helps in starting or stopping the instances individually
Instances
• Each instance is hidden from another instance• Enhances security• Every instance has its own set of Users, Admins,
Databases, Collations• Advantage of having multiple instance is
– Multi company support (Each company can have its own instance and create databases on the same server, independent on each other)
– Server consolidation (Can host up to 10 server applications on a single machine)
BCP
• Bulk Copy Program
• A powerful command line utility that enables us to transfer large number of records from a file to database
• Time taken for copying to and from database is very less
• Helps in back up and restoration
Query Analyzer
• Allows us to write queries and SQL statements
• Checks syntax of the SQL statement written
• Executes the statements
• Store and reload statements
• Save the results in file
• View reports (either as grid or as a text)
SQL Database Objects
• A SQL Server database has lot of objects like– Tables– Views– Stored Procedures– Functions– Rules– Defaults– Cursors– Triggers
System Databases
• By default SQL server has 4 databases– Master : System defined stored procedures,
login details, configuration settings etc– Model : Template for creating a database– Tempdb : Stores temporary tables. This db is
created when the server starts and dropped when the server shuts down
– Msdb : Has tables that have details with respect to alerts, jobs. Deals with SQL Server Agent Service
Creating a database
• We need to use Master database for creating a database
• By default the size of a database is 1 MB
• A database consists of– Master Data File (.mdf)– Primary Log File (.ldf)
Database operations
• Changing a databaseUse <dbname>
• Creating a databaseCreate database <dbname>
• Dropping a databaseDrop database <dbname>
SQL Server Data types
• Integer : Stores whole number• Float : Stores real numbers• Text : Stores characters• Decimal: Stores real numbers• Money : Stores monetary data. Supports 4 places
after decimal• Date : Stores date and time• Binary : Stores images and other large objects• Miscellaneous : Different types special to SQL Server.
(Refer to notes for more info)
Select Statements
• To execute a statement in MS SQL, Select the statement and Click on the Execute button in the query analyser or press F5
• This is used to retrive records from a table• Eg. Select * from table1;
– This will fetch all rows and all columns from table1• Eg. Select col1,col2 from table1
– This will fetch col1 and col2 from table1 for all rows• Eg. Select * from table1 where <<condn>>
– This will fetch all rows from table1 that satisfies a condition• Eg. Select col1,col2 from table1 where <<condn>>
– This will fetch col1 and col2 of rows from table1 that satisfies a condition
Select Options
• Aggregate functions– Sum(col1): sum of data in the column col1– Max(col1): data with maximum value in col1– Min(col1): data with minimum value in col1– Avg(col1): Average of data in col1– Count(col1): Number of not null records in table
• Grouping – Group by col1 : Groups data by col1• Ordering – Order by col1 : Orders the result in
ascending order (default order) of col1• Filtering – Where <<condn>> and Having
<<condn>>
Table management
Create table tablename(
col1 data type,col2 data type
);- Creates a table with two columns
Drop table tablename; - Drops the table structure
Insert statements
• Inserting data to all columns– Insert into tablename(col1,col2) values(v1,v2)– Insert into tablename values(v1,v2)
• Inserting data to selected columns– Insert into tablename(col1) values (v1)– Insert into tablename(col2) values (v2)
Update statement
Update table tablename
Set colname=value
- This updates all rows with colname set to value
Update table tablename
Set colname=value
Where <<condition>>
- This updates selected rows with colname as value only if the row satisfies the condition
Delete statements
Delete from table1;
Deletes all rows in table1
Delete from table1 where <<condition>>
Deletes few rows from table1 if they satisfy the condition
Truncate statement
• Truncate table tablename• Removes all rows in a table• Resets the table.
• Truncate does the following, where as delete statement does not– Releases the memory used– Resets the identity value– Does not invoke delete trigger
Alter statements
• Used to modify table structure– Add new column– Change data type of existing column– Delete a column– Add or remove constraints like foreign key,
primary key
More table commands
• Viewing tables in a data base:– Exec sp_tables “a%”– This gives all tables in the current database
that starts with “a”
• Viewing table strucure:– Exec sp_columns <<tablename>>– Exec sp_columns student;
Joins
• Cross Join– Cartesian product. Simply merges two tables.
• Inner Join– Cross join with a condition. Used to find matching
records in the two tables
• Outer Join– Used to find un matched rows in the two tables
• Self Join– Joining a table with itself
Cross Join
There are two tables A and BA has a column Id and data (1,2,3)B has a column Id and data (A,B)
If I putSelect A.Id, B.Id from A,BThis generates output as A 1B 1C 1A 2B 2C 2
Self Join
There is a table called Emp with the following structure:
empid ename mgrid
1 A null
2 B 1
3 C 1
4 D 2
If I want to print all managers using self join, I should write quey as:
select e1.ename from
emp e1,emp e2
where e1.mgrid = e2.empid
Inner Join
I have 2 tables Student(sid,Name) and Marks(Sid,Subject,Score)
If I want to print the marks of all students in the following format,
Name Subject Score
Select Name,Subject,Score from
Student s join Marks m
On s.sid = m.sid
Outer Join
• Right outer Join– Print all the records in the second table with null
values for missing records in the first table
• Left outer Join– Print all the records in the first table with null values
for missing records in the second table
• Full outer Join– Prints all records in both the table with null values for
missing records in both the table
Left Outer Join
I have a table Employee (Eid, Ename, Mid) and
a table Machine (Mid,ManufacturerName)
Employee
Eid EName Mid
1 ABC 1
2 DEF 3
Machine
Mid ManufacturerName
1 Zenith
2 HP
Left Outer Join
I want to print the employee name and machine name.
If I write a query using inner join, then the second employee will
not be displayed as the mid in his record is not avilable with the second
table.
So I go for left outer join. The query is as shown below:
Select Ename, ManufacturerName from Employee e left outer join
Machine m on e.Mid = m.Mid
Right outer Join
Assume data in the tables like this:
Employee
Eid EName Mid
1 ABC 1
2 DEF
Machine
Mid ManufacturerName
1 Zenith
2 HP
Right Outer Join
If I want to find which machine is unallocated, I can use right outer join.
The query is as follows:
Select Ename, ManufacturerName from Employee e right outer join
Machine m on e.Mid = m.Mid
This yields a result
ABC Zenith
HP
Full Outer Join
Assume data in the tables like this:
Employee
Eid EName Mid
1 ABC 1
2 DEF
3 GHI 2
Machine
Mid ManufacturerName
1 Zenith
2 HP
3 Compaq
Full Outer Join
If I want to find people who have been un allocated with a system and
machines that are been un allocated, I can go for full outer join.
Query is like this:
Select Ename, ManufacturerName from Employee e full outer join
Machine m on e.Mid = m.Mid
This yields a result
ABC Zenith
DEF
GHI HP
Compaq
Views
• Views are logical tables
• They are pre compiled objects
• We can select few columns or rows from a table and put the data set in a view and can use view in the same way as we use tables
Views
• Create views:Create view viewname as select stmtCreate view view_emp as select empid,empname from employee;
• Select from views:Select * from viewnameSelect empid,empname view_emp;
• Drop views: Drop view viewnameDrop view view_emp;
String Functions
• Substring(string,start,length) – Will fetch characters starting at a specific index extending to length specified.
• Left(string,length) – Fetches number of characters specified by length from left of the string
• Right(string,length) – Fetches number of characters specified by length from right of the string
• Len(string) – Returns the length of a string
String Functions
• Ltrim(string) – Removes leading spaces in a string
• Rtrim(string) – Removes trailing spaces in a string
• Lower(string) – Converts the characters in a string to lower case
• Upper(string) – Converts the characters in a string to upper case
Numeric Functions
• ABS(Number) – Fetches the modulo value (Positive value) of a number
• CEILING(Number) – Fetches the closest integer greater than the number
• FLOOR(Number) – Fetches the closest integer smaller than the number
• EXP(Number) – Fetches the exponent of a number
Numeric Functions
• POWER(x,y) – Fetches x raised to the power of y
• LOG(Number) – Fetches the natural logarithmic value of the number
• LOG10(Number) – Fetches log to the base 10 of a number
• SQRT(Number) – Fetches the square root of a number
Indexes
• Indexes make search and retrieve fast in a database
• This is for optimizing the select statement
• Types of index– Unique– Non unique– Clustered– Non clustered
Index
Create index indexname on
tablename(columnname)
This creates a non clustered index on a table
Create unique clustered index index_name on
Student(sname);
This creates a unique and clustered index on the
Column Sname.
Sequences
• This creates an auto increment for a column
• If a table has a column with sequence or auto increment, the user need not insert data explicitly for the column
• Sequence is implemented using the concept of Identity
Identity
• Identity has– A seed– An increment
• Seed is the initial value
• Increment is the value by which we need to skip to fetch the nextvalue
• Identity(1,2) will generate sequence numbers 1,3,5,7…