ROW Lock

Khaled Alkhudari
A free video tutorial from Khaled Alkhudari
Sr Oracle Developer/ Sr system analyst
4.5 instructor rating • 7 courses • 24,673 students

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Oracle Database 12c SQL Certified Associate 1Z0-071

Become Oracle SQL Certified ( OCA ) / Covers ORACLE university track 100%. All the presentations & scripts are attached

19:53:19 of on-demand video • Updated January 2020

  • The Full track of Oracle Database 12c: Introduction to SQL Ed 2.
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  • Very strong introduction to make you understand the oracle database and RDBMS.
  • Oracle Database 12c Architecture
  • Downloading and installing oracle database 12c in details
  • Connecting to the Database
  • Retrieving data using the select statement / Restricting and Sorting Data
  • Substitution Variables
  • Using Single-Row Functions to Customize Output
  • Reporting Aggregated Data Using the Group Functions
  • Displaying Data from multiple tables using joins
  • Using Subqueries to Solve Queries
  • Using the Set Operators
  • Managing tables using DML Statments ( Insert, Update, Delete )
  • Data Definition Language / Creating tables
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  • Creating sequences, synonyms, and indexes
  • Creating Views in details
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  • Manipulating Data
  • Managing Data in Different Time Zones
  • Exam information / Exams Details / Exam Practice
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English [Auto] Hi welcome back to day we will talk about a very important topic which is our all. Look what is the meaning of role look to understand this. I will make for you nice scenario and you will understand what is the meaning of rowlock and what does that mean of data consistency. OK so it's a now. Now I am collecting because there are user. I will make this query select to start from employees where employee ID equal 1 0 9. I will execute de-select the statement. And this is the result. You can see that the salary of the employee Daniel is NINE THOUSAND. Now I want to increment this employee by $20. So I will make a bet and please sit Sellery equal salary plus 20 were Employee ID equal ones you don't mind. I will execute this update statement. It will give me one or more updated. I would make the select on the salary now is 9000 to 20. Until now I didn't do any comment. So no I will try to go and open another session to ask you about. So I will open another session. I will connect to each other. I will drag this window to the right like this and also I will dog the original session to live like this. OK that is very nice. So no this is number one and this is session number two for the same user. So now the salary is nine thousand to 20. This session can only see these changes because the user says they don't make any comment or rollback. OK so now if you try to take the select statement going to see and put it here and try to executed. Their salary will be still 9000. So this is data consistency. Because maybe the first session she want to make a rollback. So this means I need to have a consistent. So this is called consistency. OK very nice. Now if this user in the session to try to update the sim table same wrote what will happen in this case it will be locked because you still need to wait. Thus issue number one until finish. So no I will go now. I will take this update statement. For example quintals C and I will go to the other session they use for now. He will try to make a. I will now execute. You will find now that session hanging. Why. Because there is a lock on the auto So this session it will wait until the user here take action. So now for example if they user in the first session take action and make comments for example then the other session will take response and execute the statement. It's very simple and easy. So when you do and it changes when the first session and you didn't do any comment either session cannot see the new changes and also other sessions cannot make modifications in the same row of the first session so it will make table look. So thank you for listening and see you in the next video.