You told that DUMMY column size is 1. That means varchar2(1) should store only one value/character, just like X or 1 or A or C etc. But how we are getting 100 when we execute select 20+80 from dual; Ideally it should show only 1 value/character as the size is 1. So please let me know what is the meaning of 1 in Varchar2(1). Is it allows only 1 character/value OR is there any other logic ?. If it takes 80+20 as a literal, then how ADDITION is happening???
I am addicted to ur explanation..can u please tell me how to learn reg_expressions in easiest way..every time I am feeling difficult to learn this topic
@Shahrukh, as per "INSERT ALL" statement syntax, the subquery at the end of inter all statement is mandatory, and incase if you are not planning to use any value from subquery, just to complete the syntax, you can use the dual to finish the syntactically correct statement. Hope this helps, i will post a video on insert all soon for everyone's benefits.
If dual has type of varchar2(1) then how can it accommodate 'WE' as output in substring example and even Sysdate and all which are way of more size than just varchar2(1)??
We are not actually fetching any of these values from dual table or the dummy column of dual table. for eg, select 100 from dual, in this case, the 100 is just a numeric literal, and its not getting fetched from dummy column. These will act like pesudo column, or virtual column, these were not present in table, however will act like a column of table.
Hi Siva how to handle the merge join cartesian issue while population of huge no of records i get this issue frequently in my realtime project can you make a video on how to handle it or what is the approach to handle it??
@Zulkaif, Thanks for your comment, Posted 13+ question till now on this playlist, more question i will be posting whenever i get time, please stay tuned. czcams.com/play/PLb1qVSx1k1VpEqAXgoFn5p7kFVzgsvUgM.html
Thank you so much for all your videos. It's easy to understand. I have learnt lot from your video series. Could you please make videos about Joins and types of joins.
We are not selecting number or any other datatype from varchar column, instead we are selecting a specific literal value in select clause, it will behave like a pseudo colum., not necessarily selecting from the underlying base table
You can create your own table, with one column and one row (similar to dual table), and you can use instead of dual table. If you need to access your own table across other schema, then you can grant and create synonym for that. SO technically you can use, but the dual table was created by oracle to handle all scenarios, normally we wont create our own table.
You told that DUMMY column size is 1. That means varchar2(1) should store only one value/character, just like X or 1 or A or C etc. But how we are getting 100 when we execute select 20+80 from dual; Ideally it should show only 1 value/character as the size is 1. So please let me know what is the meaning of 1 in Varchar2(1). Is it allows only 1 character/value OR is there any other logic ?. If it takes 80+20 as a literal, then how ADDITION is happening???
This video series is pure art. And Siva Sir is the artist!!!
😊🙏💐My pleasure bro
True that
very helpful information hatsoff sir
Your videos will help many people to crack the interview. Abundance knowledge. Thank you for all the efforts:)
Welcome bro
Super Bro... Ultimate Explanation..👍👍👍
Thank you so much 😀
I am addicted to ur explanation..can u please tell me how to learn reg_expressions in easiest way..every time I am feeling difficult to learn this topic
🙂 Thank you bro, I will post the same way how I learnt, please stay tuned
atlast someone with an explanation. sir can you please explain why we use select * from dual in INSERT ALL
@Shahrukh, as per "INSERT ALL" statement syntax, the subquery at the end of inter all statement is mandatory, and incase if you are not planning to use any value from subquery, just to complete the syntax, you can use the dual to finish the syntactically correct statement. Hope this helps, i will post a video on insert all soon for everyone's benefits.
very nice information thanks
@Priyanka, Thanks for your comment :-)
Thanks alot I have learnt so many things which I don't know in each and every video and have subscribed soon.
Welcome 🙏👍
If dual has type of varchar2(1) then how can it accommodate 'WE' as output in substring example and even Sysdate and all which are way of more size than just varchar2(1)??
We are not actually fetching any of these values from dual table or the dummy column of dual table. for eg, select 100 from dual, in this case, the 100 is just a numeric literal, and its not getting fetched from dummy column. These will act like pesudo column, or virtual column, these were not present in table, however will act like a column of table.
@@SivaAcademy Thank you 👍👍
nice video
very good explanation
Thanks and welcome
Really useful content. Super!
Welcome
I didn't get the 4:51 query, the one with the "Welcome". Can give more details please !
Look into this video for detailed explanation czcams.com/video/0wPqz4GqB_w/video.html
Hi Siva sir, As dual is Pesudo coloum it will be frame in same manner as our select query is framed.
Correct me if I am wrong?
Select 'A' as col_name from dual
Union All
Select '1' as col_name from dual
Output for this would be ?
Please look into this video
czcams.com/video/tK_BptiZcvg/video.html
This is awesome - thanks for sharing!
Welcome 💐
Hi Siva how to handle the merge join cartesian issue while population of huge no of records i get this issue frequently in my realtime project can you make a video on how to handle it or what is the approach to handle it??
Awesome. Can you please make videos on sql queries from interview perspective?
@Zulkaif, Thanks for your comment, Posted 13+ question till now on this playlist, more question i will be posting whenever i get time, please stay tuned.
czcams.com/play/PLb1qVSx1k1VpEqAXgoFn5p7kFVzgsvUgM.html
@@SivaAcademy i want learn function ,procedure and packages from you
Sequences used in pl/SQL without dual table sir make a video on this topic
Sure Praveen, please stay tuned
what will the query "union select(1) from dual" will return?
One of the interview questions: Will this dual table be present in all_tables like other tables?
yes✔
Nice video
@Dilip, Thanks Ji :-)
Thank you so much for all your videos. It's easy to understand. I have learnt lot from your video series. Could you please make videos about Joins and types of joins.
Thank you, sure, please stay tuned, will cover in upcoming videos
Will varchar datatype col returns numbers? If the dummy column is of varchar type how it is returning numbers? Please explain.
We are not selecting number or any other datatype from varchar column, instead we are selecting a specific literal value in select clause, it will behave like a pseudo colum., not necessarily selecting from the underlying base table
@@SivaAcademy Thanks ji got it.
Select 1*1, 2*2, 3*4 from dual
Output for this is ??
1 , 4 , 12
How to find duplicate rows without joins in sql from two tables
Not sure whether this will help you,
czcams.com/video/H47NtICRjzI/video.html
Can you make vedioes on merge sql , report and forms .
Sure Umesh, Please stay tuned.
how we ca get first 10 records?
Can we create table that have functionality same like dual table? If yes then how? PLs reply
You can create your own table, with one column and one row (similar to dual table), and you can use instead of dual table.
If you need to access your own table across other schema, then you can grant and create synonym for that. SO technically you can use, but the dual table was created by oracle to handle all scenarios, normally we wont create our own table.
What is connect by level here sir? How it works sir can you please explain sir
connect by level is part of hierarchical query, will explain in some other video, please stay tuned
Why Oracle has dual table while other database doesn't.
How to retrieve 20 or more rows from dual table .....like this quetion
Ans me this quetion
SELECT * FROM DUAL
CONNECT BY LEVEL < =20
Can we insert data into dual table
yes you can do as sys user...though we never do it, and its not recommended too
What is Dual - 0:33