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Introduction to Structured Query Language | points regarding its
Features and Syllabus
Gate Smashers
Gate Smashers is going to discuss Introduction to Introduction to SQL
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Because many times the query of
students comes that what are the topics we have to cover inside the sql ,
Whether it is about higher competitive exams or placement
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The structure data we have at today 's
time is very less
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There is no general use of
SQL so it is a particular domain where we use what is that domain ?
Relational database , that 's why we call it Domain Specific Language
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What to do happens
and how to do also that means I have to mention both things inside the
program what to do
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We use direct
application program interface and we do query like that particular day ,
I have to search any train
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I will give the most stars to this point here
because the students who get stuck the most get stuck
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In which we have also added the procedural
part in which we create triggers , create functions , create cursors , we
can also create procedures which we do in C language
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All Types of SQL Commands with Example | DDL, DML, DCL, TCL and
CONSTRAINTS | DBMS
Gate Smashers
Gate Smashers are going to discuss about types of SQL commands
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Structure data
means data that we normally store in the form of tables or relations
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DDL means data definition so the data we have to store before storing I
need a structure in which I can put that data
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commit means if the transaction is completed
commit then we will put all the values in the database
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If the transaction fails then we rollback , in Actual
acid property
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If you want to execute then you use the software
which is from Oracle
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You can use
sequel server or sequel software
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ALTER Command (DDL) in SQL with Implementation on ORACLE
Gate Smashers

Varun Singla: In today 's video we are going to discuss About ALTER
command As we had discussed in the last video In DDL the first command
about create In which we had done create table with implementation In
this video we will also do its implementation In Oracle
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Alter command is used so these are the multiple ways through which you
can Thorough Alter command you can perform all these task So come we will
see its implementation Come we will start with implementation First of
all I want to tell you Over here I have written create table command And
we are creating a table over here Employee And I have added 2 columns Id
and Name in it
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In this way we
can add , drop and modify column datatypes and along with that you can
rename So alter table Tablename Employee
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Object to be described Could not be found which means
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Table name What we have changed ? Emp11 So this
major , what we can do is With alter Add , drop , modify , rename column
Or rename table
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SQL Queries and Subqueries (part-1) | Database Management System
Gate Smashers
Gate Smashers Today I am going to discuss The practice questions on SQL
query
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We are going to write near about 7-8
queries On this topic And these whole queries We will start from very
simple From absolute beginning And we will go till end End means We will
go to complex queries
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Now this whole table will be compared With inner
query output
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Nested for loop means for 1 value of i j will go till
n
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We will discuss where
correlated queries query from source And more nested queries
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We will
find that Then , Which employee is taking second highest salary That
employees name Or Id If I want to find that employees information Then
how we will find That information
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Select salary from employee where salary ! = so always
inner query Whenever I talk about nested query So inner query Will give
output for one time It will be executed once And it will give the output
50,000 Now I want to compare this with outer salary We will compare the
values over here Over here my all the salaries have came 30,40 and 50 We
have written where salary Where salary From employee table Where salary

means You write value of all salaries over here Not equal to Inner query
output What is inner query output? We print second highest salary so
second highest is printed over here This is the logic
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The one who can frame queries Can apply logic He can solve all the
queries And I have already told that this is the only topic Where
students in interviews are asked about queries
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Groupby
clause help so how do we write groupby clause ? Select Select We will see
afterwards that what is to be selected From employee table This is the
important part When SQL query is executed First of all from We have to
start to execute first from Table first of all table From table name
Groupby
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How many
employees are there in each department For that what I have to apply over
here Count function How ? Select department , count * Count * Select
department Select department obviously Department is over here so I can
use department Other than that We can use only the aggregate function
Select department
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2 means
1 So It should be the output So for that this video It is totally linked
Even all the sub queries series that I am making are linked with each
other
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I do n't know where
randomly HR is Because I can sort employee id easily If I talk about
department Then even if I want to sort department Then What is the
advantage ? There is no advantage HR ones , what is the meaning of
sorting ? That we can just display in the output
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tell the name of that employee
Who , is working in such department Where number of employees are less
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2 employees The department with less than two
employees Who all are working in that Tell
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The concept of nested queries is a bit complex to frame queries
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Max
means if you want to find the maximum value Minimum value Count means ,
total number of values In a table Average and sum Max means
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salary
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Minimum value means we have to use Min Min
function so select minimum value Minimum value
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Then, we use count We can use count as There is a simple method , select
count ( *) Null means Anything Null means the value that is empty Then
why we should consider it into count ? We will not count null because
when we will count in salary
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average ( Salary )
Sum is 1,40,000 and what is the count ? 1,2,3,4,5 Because it will not
take null into count And we have not used distinct So rows will come in
the output
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aggregate functions
that we have It is very easy to use them We can use it in a query easily
But when we will do nested queries In nested queries or correlated
queries These aggregate functions are used many times
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