Tricky sql queries for interview - SQL Tutorial

Tricky SQL queries for interview: In this tutorial, I will show you "tricky SQL queries for the interview" which will help you to crack your SQL interview. These SQL queries not for the fresher level (not for experience level)

Tricky sql queries for interview - SQL Tutorial


1) SQL queries to create the database
      Create database dbname

     Note:-
     *A database can’t be dropped while it will be in use or running mode.
*To drop a database we have to use another database but it will also not
dropped till it will be in running mode

     2) SQL queries to drop a database
Drop database dbname (It will be dropped using another database if it will not be in use)

     3) SQL queries to rename  a database
sp_renamedb 'dbName','NewdbName'

4) SQL queries to create a table
create table Emp
(
RID int primary key identity(1,1),
Name varchar(50),
Age int,
salary int
)

     5) Sql queries to rename a table
sp_rename 'Emp','employee'

     6) Sql queries to rename a column
sp_rename'employee.Age','emp_age'

     7) Sql queries to alter data type of column
alter table employee alter column emp_age varchar.

Note:(a datatype of the column cannot be changed when it will have data  inside it and it can be changed also when it will have data too but only in case of upcasting  ex:- int to varchar)

     8) Sql queries to add a new column in table
altert table employee add gender varchar(50)
alter table employee add EmailId varchar(50)
alter table employee add EmpID int(50)

Note: The alter keyword is used for changing the definition of the database object(like procedure, function, and table )

     9)To drop a column from the table
alter table employee drop column gender



Some Select commands to fetch record from SQL


     10)To fetch two and more records from the table on the basis of the ID
select*from employee where ID=or ID=5
output:-  ID   NAME      AGE    SALARY

2        Karan        24      23222
5        virat           28      10000000

11)To find the same using IN function
select*from employee where ID in(2,4)
output:-    ( ID, name,   age, salary)
2    Karan    24  23222
4    Mohan   76  29977

12) Another query using not operator find except the given id
select*from employee where RID not in(2,4)
output:- ( RID, NAME, AGE,SALARY)
1    yogesh    23    25000
3    Ethen      08   200
5    virat        28  10000000
6    sachin     41   19000000


13) To select or fetch data between two no.’s
select*from employee where RID between 3 and 5
output:- ( ID, NAME, AGE, SALARY)
3      Ethen     08     200
4      Mohan  76     29977
5      virat      28     10000000

(whenever we will use between function then it’ll always consider start and end no. Ex:- if we want to select 2,4,5,6 then provide range from 2 to 6 including 1st and last)

14)To select data in order of name(use of order by)
select*from employee order by Name
output:- (ID,  NAME,  AGE,  SALARY)
3      Ethen    08       200
2      Karan    24       23222
4      Mohan   76       29977
6      sachin    41      19000000
5      virat      28      10000000
1      yogesh   23      25000

We use here desc to display data in descending order using this query
select*from employee order by Name desc
output:-
1 Yogesh   23   25000
5 Virat      28  10000000
6 Sachin    41  19000000
4 Mohan    76  29977
2 Karan     24  23222
3 Ethen     08  200
  
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