How quotation works in Dynamic Sql

How the Dynamic SQL Works ?

set @sSQL='Insert into #tempBusDetails(Bus_Route_ID ,Bus_Route_Name ,Vehicle_No,Max_Occupacy,
                                       Current_Occupacy ,Driver_Name ,Driver_Mobile_No ,Assistant_Name ,Assistant_Mobile_No,Hub_ID,HTML_StopName)
              SELECT distinct(bd.Bus_Route_ID),bd.Bus_Route_Name, bd.Vehicle_No, bd.Max_Occupacy, dbo.Current_Count(bd.Bus_Route_ID) AS User_Count, bd.Driver_Name,
                   bd.Driver_Mobile_No,bd.Assistant_Name, bd.Assistant_Mobile_No, f.Facility_Name, dbo.fnc_CreateHTML_StopName(bd.Bus_Route_ID) AS HTML_StopName
              FROM dbo.tbl_Bus_Details AS bd
              INNER JOIN dbo.tbl_Facility AS f ON bd.Hub_ID = f.Facility_ID
              INNER JOIN dbo.tbl_stop_details as sd on sd.Bus_route_id=bd.bus_route_id
              WHERE bd.Inactive='+cast(@Inactive as varchar)+ ''

We have the doubt in the quotation mark(in the last line).
 
--> WHERE bd.Inactive='+cast(@Inactive as varchar)+ ''
 
-->is it like bd.Inactive=' (This quotation is end of start quote). If yes then why do we need the last two quotes(+ '').
 

-->or is it like this is wrapped in single quotes : '+cast(@Inactive as varchar)+ '. And the final quotation is closed for start quote.
 
Kindly guide me.

Answer : It like this is wrapped in single quotes : '+cast(@Inactive as varchar)+ '. And the final quotation is closed for start quote.

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Question 2:

Example1:

declare @var varchar(max)
set @var='select * from tbl_user_master where first_name like'+ '''%anurag%'''
print @var
exec (@var)
--We get the result


Example2:
declare @var varchar(max)
 
set @var='select * from tbl_user_master where first_name like '''%anurag%''' '
print @var
 
exec (@var)

--Error 
what is the difference between example1 and example2?
Answer
<<<First Example >>>
like' + '''%anurag%'''
    ^   ^^^        ^^^---- Close second string
    |   |||        ||----- 2nd character of a pair of quotes\
    |   |||        |                                         - These create a single ' character
    |   |||        |------ 1st character of a pair of quotes/
    |   |||--------------- 2nd character of a pair of quotes\
    |   ||                                                   - These create a single ' character
    |   ||---------------- 1st character of a pair of quotes/
    |   |----------------- Open second string
    |--------------------- Close first string                       

<<<Second Example>>>


like '''%anurag%''' '
     |||        ||| |----- Or this...
     |||        |||------- Or this...
     |||        ||-------- Or this...
     |||        |--------- SQL not going to look at this...
     |||                   ERK! SQL NO UNDERSTAND! **REDO FROM START** ***OUT OF CHEESE ERROR***
     |||------------------ End of first string
     ||------------------- 2nd character of a pair of quotes\
     |                                                       - These create a single ' character
     |-------------------- 1st character of a pair of quotes/


Hope you liked it :) Happy coding. If this has helped you, kindly feel free to comment.