Basic Introduction & Overview of Advance SQL

iFour Consultancy Advance SQL

https://www.ifourtechnolab.com/

SQL Commands ➢ Some of the most important SQL Commands

• • • • • • • • • • •

SELECT - extracts data from a database UPDATE - updates data in a database DELETE - deletes data from a database INSERT INTO - inserts new data into a database CREATE DATABASE - creates a new database ALTER DATABASE - modifies a database CREATE TABLE - creates a new table ALTER TABLE - modifies a table DROP TABLE - deletes a table CREATE INDEX - creates an index (search key) DROP INDEX - deletes an index

https://www.ifourtechnolab.com/

SQL CREATE DATABASE Statement ➢ Used to create a database • CREATE DATABASE dbname;

➢ Database tables can be added with the CREATE TABLE statement

https://www.ifourtechnolab.com/

SQL CREATE TABLE Statement ➢ It is used to create a table in a database ➢ Tables are organized into rows and columns; and each table must have a name ➢ Syntax

CREATE TABLE table_name ( column_name1 data_type(size), column_name2 data_type(size), column_name3 data_type(size), .... ); ➢ The column_name parameters specify the names of the columns of the table ➢ The data_type parameter specifies what type of data the column can hold ➢ The size parameter specifies the maximum length of the column of the table

https://www.ifourtechnolab.com/

SELECT Statement ➢ Used to select data from a database ➢ The result is stored in a result table, called the result-set ➢ SQL SELECT Syntax:

SELECT column_name,column_name FROM table_name; SELECT * FROM table_name;

and

https://www.ifourtechnolab.com/

INSERT INTO Statement ➢ Used to insert new records in a table ➢ It is possible to write the INSERT INTO statement in two forms ➢ The first form does not specify the column names where the data will be inserted, only

their values: INSERT INTO table_name VALUES (value1,value2,value3,...); ➢ The second form specifies both the column names and the values to be inserted:

INSERT INTO table_name (column1,column2,column3,...) VALUES (value1,value2,value3,...);

https://www.ifourtechnolab.com/

SQL UPDATE Statement ➢ Used to update existing records in a table ➢ SQL UPDATE Syntax UPDATE table_name SET column1=value1,column2=value2,... WHERE some_column=some_value;

https://www.ifourtechnolab.com/

SQL DELETE Statement ➢ Used to delete records in a table ➢ SQL DELETE Syntax:

DELETE FROM table_name WHERE some_column=some_value; ➢ It is possible to delete all rows in a table without deleting the table. This means that the

table structure, attributes, and indexes will be intact: DELETE FROM table_name; or DELETE * FROM table_name;

https://www.ifourtechnolab.com/

SQL Group By Statement ➢ Used in conjunction with the aggregate functions to group the result-set by one or more

columns ➢ SQL GROUP BY Syntax: SELECT column_name, aggregate_function(column_name) FROM table_name WHERE column_name operator value GROUP BY column_name;

https://www.ifourtechnolab.com/

SQL having Clause ➢ The HAVING clause was added to SQL because the WHERE keyword could not be used with

aggregate functions ➢ SQL HAVING Syntax: SELECT column_name, aggregate_function(column_name) FROM table_name WHERE column_name operator value GROUP BY column_name HAVING aggregate_function(column_name) operator value;

https://www.ifourtechnolab.com/

SQL Joins ➢ Used to combine rows from two or more tables ➢ It is used to combine rows from two or more tables, based on a common field between

them ➢ The most common type of join is: SQL INNER JOIN (simple join) ➢ An SQL INNER JOIN return all rows from multiple tables where the join condition is met

https://www.ifourtechnolab.com/

Types Of JOINs ➢ Different SQL JOINs • INNER JOIN: Returns all rows when there is at least one match in BOTH tables

Syntax: SELECT table1.Column_name,table2.Column_name FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name; • LEFT JOIN: Return all rows from the left table, and the matched rows from the right table

Syntax: SELECT table1.Column_name,table2.Column_name FROM table1 LEFT OUTER JOIN table2 ON table1.column_name=table2.column_name;

https://www.ifourtechnolab.com/

Types Of JOINs • RIGHT JOIN: Return all rows from the right table, and the matched rows from the left table

Syntax: SELECT table1.Column_name,table2.Column_name FROM table1 RIGHT OUTER JOIN table2 ON table1.column_name=table2.column_name; • FULL JOIN: Return all rows when there is a match in ONE of the tables

Syntax: SELECT table1.Column_name,table2.Column_name FROM table1 FULL OUTER JOIN table2 ON table1.column_name=table2.column_name;

https://www.ifourtechnolab.com/

Types Of JOINs ➢Different SQL JOINs

SELF JOIN: It is used to join a table to itself as if the table were two tables, temporarily renaming at least one table in the SQL statement Syntax: SELECT a.column_name, b.column_name FROM table1 a, table1 b WHERE a.common_field = b.common_field;

Example SELECT a.ID, b.NAME, a.SALARY FROM CUSTOMERS a, CUSTOMERS b b.SALARY;

https://www.ifourtechnolab.com/

WHERE a.SALARY <

Stored Procedure ➢ It is a group of sql statements that has been created and stored in the database. ➢ It will accept input parameters so that a single procedure can be used over the network by

several clients using different input data ➢ It will reduce network traffic and increase the performance. If we modify stored procedure all the clients will get the updated stored procedure ➢ Syntax: CREATE PROCEDURE dbo.sp_who AS SELECT FirstName, LastName FROM Person.Person; GO EXEC sp_who; GO

https://www.ifourtechnolab.com/

Function ➢ Special kind stored program that returns a single value ➢ You use functions to encapsulate common formulas or business rules that are reusable

among SQL statements or stored programs ➢ Syntax: CREATE FUNCTION function_name(param1,param2,…)

RETURNS datatype [NOT] DETERMINISTIC statements

https://www.ifourtechnolab.com/

Difference Between Function and Stored Procedure Function

Stored Procedure

It must return a value

In Stored Procedure it is optional( Procedure can return zero or n values)

It will allow only input parameters, doesnâ&#x20AC;&#x2122;t support output parameters

It can have input/output parameters

It can be called from Procedure

It cannot be called from Function

Allows only SELECT statement in it

It allows SELECT as well as DML(INSERT/UPDATE/DELETE) statement in it

It will not allow us to use try-catch blocks

For exception handling we can use try catch blocks

We can use only table variables, it will not allow using temporary tables

It Can use both table variables as well as temporary table in it

It can be called from a select statement

It canâ&#x20AC;&#x2122;t be called from Select/Where/Having and so on statements.

Execute/Exec statement can be used to call/execute Stored Procedure

https://www.ifourtechnolab.com/

Views ➢ In some cases, it is not desirable for all users to see the entire logical model (that is, all the

actual relations stored in the database) ➢ Consider a person who needs to know a customer’s name, loan number and branch name, but has no need to see the loan amount. This person should see a relation described, in SQL, by (select customer_name, borrower.loan_number, branch_name from borrower, loan where borrower.loan_number = loan.loan_number ) ➢ It provides a mechanism to hide certain data from the view of certain users ➢ Any relation that is not of the conceptual model but is made visible to a user as a “virtual

relation” is called a view

https://www.ifourtechnolab.com/

Views (Cont.) â&#x17E;˘ A view consisting of branches and their customers:

create view all_customer as ( select branch_name, customer_name from depositor, account where depositor.account_number = account.account_number ) union ( select branch_name, customer_name from borrower, loan where borrower.loan_number = loan.loan_number )

https://www.ifourtechnolab.com/

Triggers ➢ Special kind of a stored procedure that executes in response to certain action on the table like insertion, deletion or updating of data. ➢ It is a database object which is bound to a table and is executed automatically. You can’t explicitly invoke triggers. ➢ Types of Triggers • After Triggers (For Triggers) • Instead Of Triggers

https://www.ifourtechnolab.com/

Triggers ➢After Triggers (For Triggers) • These triggers run after an insert, update or delete on a table, they are not supported for views • AFTER TRIGGERS can be classified further into three types as: • AFTER INSERT Trigger - This trigger is fired after an INSERT on the table • AFTER UPDATE Trigger - This trigger is fired after an update on the table • AFTER DELETE Trigger - This trigger is fired after a delete on the table

https://www.ifourtechnolab.com/

Triggers ➢Instead of Triggers • These can be used as an interceptor for anything that anyone tried to do on our table or view • INSTEAD OF TRIGGERS can be classified further into three types as: • INSTEAD OF INSERT Trigger - This trigger is fired instead of an INSERT on the table • INSTEAD OF UPDATE Trigger - This trigger is fired instead of an update on the table • INSTEAD OF DELETE Trigger - This trigger is fired instead of a delete on the table

https://www.ifourtechnolab.com/

Triggers â&#x17E;˘ Example Of Trigger CREATE TRIGGER trgAfterInsert ON [dbo].[Employee_Test] (FOR|After|INSTEAD OF) (INSERT|Update|Delete) AS declare @empid int; declare @empname varchar(100); declare @empsal decimal(10,2); declare @audit_action varchar(100);

select @empid=i.Emp_ID from inserted i; select @empname=i.Emp_Name from inserted i; select @empsal=i.Emp_Sal from inserted i; set @audit_action='Inserted Record -- After Insert Trigger.'; insert into Employee_Test_Audit (Emp_ID,Emp_Name,Emp_Sal,Audit_Action,Audit_Timestamp) values(@empid,@empname,@empsal,@audit_action,getdate()); PRINT 'AFTER INSERT trigger fired.'

GO

https://www.ifourtechnolab.com/

Cursor (cont.)

FETCH [NEXT|PRIOR|FIRST|LAST|ABSOLUTE n|RELATIVE n] FROM [GLOBAL] cursor_name INTO @Variable_name[1,2,..n] CLOSE cursor_name --after closing it can be reopen

DEALLOCATE cursor_name --after deallocation it can't be reopen

https://www.ifourtechnolab.com/

Cursor ➢Database object to retrieve data from a result set one row at a time, instead of the T-SQL commands that operate on all the rows in the result set at one time. ➢Use cursor when we need to update records in a database table in singleton fashion means row by row. ➢Syntax DECLARE cursor_name CURSOR [LOCAL | GLOBAL] --define cursor scope [FORWARD_ONLY | SCROLL] --define cursor movements (forward/backward) [STATIC | KEYSET | DYNAMIC | FAST_FORWARD] --basic type of cursor [READ_ONLY | SCROLL_LOCKS | OPTIMISTIC] --define locks FOR select_statement --define SQL Select statement FOR UPDATE [col1,col2,...coln] --define columns that need to be updated OPEN [GLOBAL] cursor_name --by default it is local

https://www.ifourtechnolab.com/

Cursor â&#x17E;¢Example Of Cursor SET NOCOUNT ON DECLARE @Id int DECLARE @name varchar(50) DECLARE @salary int DECLARE cur_emp CURSOR STATIC FOR SELECT EmpID,EmpName,Salary from Employee OPEN cur_emp IF @@CURSOR_ROWS > 0 BEGIN FETCH NEXT FROM cur_emp INTO @Id,@name,@salary WHILE @@Fetch_status = 0 BEGIN PRINT 'ID : '+ convert(varchar(20),@Id)+', Name : '+@name+ ', Salary : '+convert(varchar(20),@salary) FETCH NEXT FROM cur_emp INTO @Id,@name,@salary END END CLOSE cur_emp DEALLOCATE cur_emp SET NOCOUNT OFF

https://www.ifourtechnolab.com/

Version history (2000,2005,2008,2012) Sql-2000

Sql-2005

1) No XML data type is introduced

XML data type is introduced

2) We can create maximum of 65535 databases

We can create 2(pow(20))-1 databases

3) Exception handling is not here

Exception handling is there

4) can't compress the tables and indexes

Can compress the table and indexes

5) No varchar(max) or varbinary(max) is available

varchar(max) or varbinary(max) is available

6)Pivot and Unpivot function are not used

Pivot and Unpivot function are used

7) Can't bulk copy update

Bulk copy update

8) Can't encrypt the database

Can encrypt the database

https://www.ifourtechnolab.com/

Version history (2000,2005,2008,2012) (cont.)

Sql-2005

Sql-2008

1) Doe's not provide backup encryption

Introduced Back-Up encryption

2) XML Data type is introduced

XML Data type is implemented and used

3)File stream is not there

File stream is introduced

4)Linq is not there

Linq is introduced for retrieving multiple type of data

5)Merge statement is not included

Merge statement is included

6)Table-valued parameter is not there

Table-valued parameter is introduced

7)Data Synchronization is not introduced

Data synchronization is introduced

https://www.ifourtechnolab.com/

Version history (2000,2005,2008,2012) (cont.)

Sql-2008 1) it support maximum of 64 logical process

Sql- 2008-r2 It support maximum of 256 logical process

2) Master data services part of BI is not included Master Data service part of Bi is included in sqlin sql-2008 2008r2 3)Power Pivot in BI is not implemented

Power Pivot Bi is implemented

4) introduced geospatial data types with few common feature in ssrs2008

Add geospatial data types in ssrs 2008

https://www.ifourtechnolab.com/

Version history (2000,2005,2008,2012) (cont.)

Sql-2008

Sql- 2012

1)It can support only 1000 partition

It can support 15000 partition

2) Sql server 2008 uses 27 bit precision for spatial

Sql server 2012 uses 48 bit precision for spatial

3) String function concate and format are not available

String function concate and format are available

4) Analysis services in sql server not have Bi concept

Analysis services will include a new BISM with 3 Layer model

https://www.ifourtechnolab.com/

SQL Server 2014 Features ➢ New cardinality estimator • Improves the execution plans that we're seeing for some of our more complex queries, and definitely assists with the ascending key problem ➢ AlwaysOn enhancements • Microsoft has enhanced AlwaysOn integration by expanding the maximum no of secondary replicas from 4 to 8.

• Readable secondary replicas are now also available for read workloads, even when the primary replica is unavailable.

In addition, SQL Server 2014 provides the new Add Azure Replica Wizard, which helps you create asynchronous secondary replicas in Windows Azure. ➢ Delayed durability • It is a way to defer the acknowledgement of the transaction log records getting written to disk - which means your transaction can continue without waiting, and assume that the log record *will* be written. ➢ In-Memory OLTP • SQL Server 2014 enables memory optimization of selected tables and stored procedures.

• The In-Memory OLTP engine is designed for high concurrency and uses a new optimistic concurrency control mechanism to eliminate locking delays • Microsoft states that customers can expect performance to be up to 20 times better than with SQL Server 2012 when using this new feature.

https://www.ifourtechnolab.com/

SQL Server 2014 Features ➢ Updateable columnstore indexes • Columnstore indexes in SQL Server 2014 brought a dramatic boost to data warehouse performance, but with a hitch: They couldn't be updated. With SQL Server 2014, now they can.

• This means you no longer have to drop and re-create columnstore indexes every time you need to load your warehouse tables. Not only that, but updateability also means you may be able to look at columnstore indexes for certain OLTP applications. ➢ SSD buffer pool extension • SQL Server 2014 provides a new solid state disk (SSD) integration capability that lets you use SSDs to expand the SQL Server 2014 Buffer Pool as nonvolatile RAM (NvRAM).

• With the new Buffer Pool Extensions feature, you can use SSD drives to expand the buffer pool in systems that have maxed out their memory. Buffer Pool Extensions can provide performance gains for read-heavy OLTP workloads. ➢ Storage I/O control • The Resource Governor lets you limit the amount of CPU and memory that a given workload can consume. SQL Server 2014 extends the reach of the Resource Governor to manage storage I/O usage as well.

• The SQL Server 2014 Resource Governor can limit the physical I/Os issued for user threads in a given resource pool.

https://www.ifourtechnolab.com/

SQL Server 2016 compared to SQL 2014 ➢ Query Store • The Query Store feature maintains a history of query execution plans with their performance data, and quickly identifies queries that have gotten slower recently, allowing administrators or developers to force the use of an older, better plan if needed. ➢ Polybase • This feature will benefit you if your regular data processing involves dealing with a lot of large text files, they can be stored in Azure Blob Storage or Hadoop, and queried as if they were database tables ➢ Stretch Database • The basics of Stretch Database are that some part of your tables (configurable or automated) will be moved into an Azure SQL Database in the cloud in a secure fashion.

• When you query those tables, the query optimizer knows which rows are on your server and which rows are in Azure, and divides the workload accordingly. ➢ JSON Support • Providing the ability to quickly move JSON data into tables

https://www.ifourtechnolab.com/

SQL Server 2016 compared to SQL 2014 ➢ Row Level Security • This restricts which users can view what data in a table, based on a function.

• SQL Server 2016 introduces this feature, which is very useful in multi-tenant environments where you may want to limit data access based on customer ID.

➢ Always Encrypted • Always Encrypted is new functionality through the use of an enhanced client library at the application so the data stays encrypted in transit, at rest and while it is alive in the database

➢ In-Memory Enhancements • Optimally designed for high-speed loading of data with no locking issues or high-volume session state issues

https://www.ifourtechnolab.com/

Practical ➢Create SQL Queries using below SQL commands • SELECT, UPDATE, DELETE, INSERT INTO, CREATE DATABASE, ALTER DATABASE, CREATE TABLE, ALTER TABLE, DROP TABLE ➢Create stored procedure for getting all employees, insert employee, update employee, delete employee ➢Create stored procedure for getting all Departments and Employee exams, insert, update and delete employee exam detail ➢Use SQL Joins for getting Employee with Department and Exam Detail ➢Create trigger for store employee data changes history ➢Create cursor for Update employee data ➢Create view for getting employee data

https://www.ifourtechnolab.com/