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MS SQL Server
Name: Janas KhanPresentation:General Discussion With Friends
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 database
Use <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)
Operators• Arithmetic• Assignment• Comparison• Logical• String• Unary• Bitwise
14
SQL statement processing order
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 managementCreate 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 JoinThere 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 JoinThere 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 JoinI 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 JoinI 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 JoinI 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 JoinAssume data in the tables like this:
Employee
Eid EName Mid
1 ABC 1
2 DEF
Machine
Mid ManufacturerName
1 Zenith
2 HP
Right Outer JoinIf 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 JoinAssume 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 JoinIf 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
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…