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Mssql

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  • Use master; Create database dbtest On primary ( name = softsmith, filename = ‘c:\\test\\softsmith.mdf’, size = 10 MB, maxsize = 20, filegrowth = 2 ) Log on ( name = softsmithlog, filename = ‘c:\\test\\softsmith.ldf’, size = 10 MB, maxsize = 20, filegrowth = 2 ) This creates a database with the name softsmith. The datafile softsmith.mdf and log file softsmith.ldf will be created in the path c:\\test. The size of database is 10 MB.
  • Integer: Bit - 1 bit Tinyint - 1 byte Smallint - 2 bytes Int - 4 bytes Bigint - 8 bytes Float: Float Real Text: Non unicode string: A character occupies 1 byte Char Varchar Text Unicode string: A character occupies 2 bytes Nchar Nvarchar Ntext Decimal: has precision and scale Decimal(p,s) Numeric(p,s) P = total digits in a number S = number of digits after decimal point Eg. Numeric(4,2) can store 22.56 and so on Money: Data like 23.2234 Money Smallmoney Date: Smalldatetime – Range – 1-1-1900 to 6-6-2079 Datetime - Range – 1-1-1753 to 31-12-9999 Binary: Binary Varbinary Image Misc: Uniqueidentifier – Unique id – can be accessed and modified through function getUid() and setUid() Cursor – Special data type meant for row by row operation Sql_variant – Generic data types Table – table data type – stores table data Timestamp – Uniqe value in a database
  • Arithmetic : +, -, *, /, % Assignment : = Comparison : , = <>, =, !=, ! Logical : AND, OR, NOT, IN, LIKE, BETWEEN, ANY, ALL, EXISTS, SOME String : Concatenation (+) Unary : -, +, ~ Bitwise: &, |, ^
  • To execute a statement in MS SQL, Select the statement and Click on the Execute button in the query analyser or press F5
  • To select distinct rows, we need to use the distinct key word Select distinct name from orders; Orders -------- Id Name -- ------- 1 Ram 2 Krish 3 Ram 4 Raj Will fetch Ram Krish Raj Select count(name) from orders; will yield the result as 4 Sum, max, min, avg can be applied only on numbers. Select sum(id) from orders will yield the result as 10 Select max(id) from orders will yield the result as 4 Select min(id) from orders will yield the result as 1 Select avg(id) from orders will yield the result as 2.5 Order by Select * from Orders order by name; 2 Krish 4 Raj 1 Ram 3 Ram Select * from Orders order by name desc; 3 Ram 1 Ram 4 Raj 2 Krish Where: Select * from orders where name = ‘Raj’; will result in Id Name -- ------- 4 Raj Having: Select Name, count(id) from Orders Group by name Having count(id) > 1 This will display names and number of occurances of name from orders table if the number of occurances Is > 1 Name count(id) Ram 2 If we miss the having, it simply displays Name and occurance of name in the table. Select Name, count(id) from Orders Group by name Name count(id) Krish 1 Raj 1 Ram 2
  • create table Student ( sid int, sname varchar(20) ) Drop table student;
  • insert into Student values(1,'Ramu') insert into Student(sid,sname) values(6,'Raj') insert into Student(sid) values(2) insert into Student(sname) values('Seetha')
  • update student set sid=3 This will set sid =3 for all students update student set sid=1 where sname='Ramu‘ This will set sid as 1 only for Ramu
  • delete from student where sid between 1 and 3 This will delete students with sid 1,2,3
  • Add new column: Alter table test add grade char(1); Modify a column data type: Alter table test alter column grade varchar(10); Delete a column: Alter table test drop column grade;

Mssql Mssql Presentation Transcript

  • Name: Janas KhanPresentation:General Discussion With FriendsMS SQL Server
  • 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 database Create database <dbname>• Dropping a database Drop 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 columnsDrop 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 statementUpdate table tablenameSet colname=value - This updates all rows with colname set to valueUpdate table tablenameSet colname=valueWhere <<condition>> - This updates selected rows with colname as value only if the row satisfies the condition
  • Delete statementsDelete from table1; Deletes all rows in table1Delete 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 asA1B1C1A2B2C2
  • Self JoinThere is a table called Emp with the following structure:empid ename mgrid1 A null2 B 13 C 14 D 2If I want to print all managers using self join, I should write quey as:select e1.ename fromemp e1,emp e2where 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 ScoreSelect Name,Subject,Score fromStudent s join Marks mOn 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) anda table Machine (Mid,ManufacturerName)EmployeeEid EName Mid1 ABC 12 DEF 3MachineMid ManufacturerName1 Zenith2 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 willnot be displayed as the mid in his record is not avilable with the secondtable.So I go for left outer join. The query is as shown below:Select Ename, ManufacturerName from Employee e left outer joinMachine m on e.Mid = m.Mid
  • Right outer JoinAssume data in the tables like this:EmployeeEid EName Mid1 ABC 12 DEFMachineMid ManufacturerName1 Zenith2 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 joinMachine m on e.Mid = m.MidThis yields a resultABC Zenith HP
  • Full Outer JoinAssume data in the tables like this:EmployeeEid EName Mid1 ABC 12 DEF3 GHI 2MachineMid ManufacturerName1 Zenith2 HP3 Compaq
  • Full Outer JoinIf I want to find people who have been un allocated with a system andmachines that are been un allocated, I can go for full outer join.Query is like this:Select Ename, ManufacturerName from Employee e full outer joinMachine m on e.Mid = m.MidThis yields a resultABC ZenithDEFGHI 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 stmt Create view view_emp as select empid, empname from employee;• Select from views: Select * from viewname Select empid,empname view_emp;• Drop views: Drop view viewname Drop 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…