Audio Transcript Auto-generated
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good morning.
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Once more Rescue bacteria t class.
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So today we are going to start our fourth unit
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that is deep database management system before getting into the
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top. I'm having a doubt.
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See, uh, I'm having a Gmail account, and I think
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most off you also have a Gmail a contract when
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we consider in the worldwide many millions and millions off
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users out there who are using female accounts right on
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dhe in my meal, there were more than 15,000 off
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mills. Other.
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Similarly, each person's, uh, it's person may have more than
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maybe more than that anyway.
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Oh, huge amount of data will be there, right?
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Videos will be their images will be, there Means will
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be there.
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How does Google handling this much data?
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Very securely and accurately.
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How does this happening?
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Which is very hectic job right, what they are doing
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in very great way, because not even one time I'm
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able to get into another persons account without their password
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and 80 it.
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So that's the topic that we are going toe study
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in this unit.
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How the data is, how that type off Data's were
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handled, Mickey.
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So for handling that types off data.
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That is huge amount of data that is called database.
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We use a software called BBM s database management system
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for managing the data in a database.
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There are different types of Softwares are available.
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One off that software is our d P M s.
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That is relational database management system.
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That is what we are going toe Charlie ec e.
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Let's have a look on that.
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So are the Bemis is a relational database management system
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here. The data's are stored as tables as you know
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the tables means it comes is off rose on dhe
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columns, Right, So here the data's are also stored as
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Rosen columns.
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Nikki. Now we are going to learn the important components
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in olive.
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Okay, first one is table, then record or trouble field
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or column name or attribute and keys.
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These are the basic components.
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N R b B M s in detail.
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What didn't Big people.
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A table is a collection off data represented in rows
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and columns.
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These table has a name in data bees.
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So a table is where something is where the data
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are stored and Rosen columns on each table should have
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a table.
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Me here you can see an example and you can
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see a table, right?
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The name off the table is called Employ, which is
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used to store the details often employ okay.
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And the terms that you are going to studies first
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is a tribute.
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Attributes is also on his column, name or field.
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The key attributes are also called column.
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Names are filled.
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You're the column names I e employees First name, last
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name, salary cookie, then comes to tubules.
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Pupils means the rolls off the table.
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Tubules is a rose offer table.
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Here, you can see as n 001 Amish Dubay 60,000.
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This will be the This will be 12 people or
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one room on this.
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This one rogue can also called a record.
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Okay, This complete role is also called a record on
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tables can be also called us a relation to relation.
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I hope all of you understand Understood the basic terms.
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Okay, that is stable then attribute off field or colony.
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Then you have learned to bulls.
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Then you have called record than relation.
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These are the basic terms that we are going toe
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use enough.
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Yeah. Okay.
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Yeah. So one more thing that you have to be
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aware while you are using database management system is null
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value. This is very important.
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Now, value.
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No value means a column, which contains nothing.
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Okay, We represent it way now, Okay.
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And you double l.
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Now, which means it contains nothing.
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Okay, so the thing you have tow careful is that
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non value and zero are two different things now.
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Value means it has nothing.
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Zero means the value off that column is 00 means
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it's a value.
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It's a constant now, the elements it doesn't have anything
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doesn't hold anything.
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The weekend enter values inside that color, but zero means
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it has a value, and that value is zero.
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These two things are different.
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Okay. I hope you understood this.
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So the next one is constrained.
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So can strength means set off rules that we are
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giving for its column or each attributes.
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Okay, These are used to limit the type off data
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that can go into a table.
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This ensures the accuracy and reliability off the data in
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the data.
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This I will say an example, like, see, uh, if
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you're using a t M cards.
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Okay. God's what happens uh, the East 18 gods have
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a limit off withdrawing the federal off money from Anita
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count. Okay, maybe my a t m card is having
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only 25,030.
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I can withdraw only up to ₹25,000 party from it.
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Eight year.
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So that is sent there.
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If I'm trying toe withdraw more than 25,000 a message
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mint. Pop up like you are.
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Limit off.
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Withdraw Something like that you are.
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Limit exceeds you are your daily limit exceeds withdrawal limits
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like seeds.
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Something like that.
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Any message will pop, right?
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So that is set in the database in your our
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data. In your letter in your account, it is said
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that you are daily limit off the dribble off money
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is 25,000.
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That is set in my data bit.
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That's why I'm not ableto we draw more than 25,000.
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Picky. So there are different types of constraints.
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Other Just have a look on that the first one
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is not null, as I said now means nothing.
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Not now means it should contain some value.
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If I will say we can take, um example like
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students table in a school We have a database called
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student tables here.
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All the students name will be there at mission number
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will be their Their phone number will be there.
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The class they're studying will be there.
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Suppose that's my table.
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And not now as it in which follow it is
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very important in this table, that is admission number.
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Name. Um Then what class phone number you're not now
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means a column, which should contain a value.
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Okay, that is admission number.
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That means every student in our school should have admission
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number. That is mandatory.
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Right? So I will set that column us?
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Not null.
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Okay, then default.
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Constrain. So we can set a default value for a
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column. Suppose, um, like a default value for them.
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Worker I'm setting.
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Ah, minimum beaches A 6000.
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So if I'm not entering any value on that column,
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it will be a riffle worth six 1000.
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That is my default.
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By automatically, it will fill it.
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But it with that value, then what about unique?
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Unique means it should be would, um, unique.
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It should be unique.
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It means the data should not be repeated in Jakarta.
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Just we can take that mission number is there is
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any student who is having a, um the same admission
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number as that other students.
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No. So admission number should be unique, right?
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For a student on admission number should be there.
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And that admission number should be unique and comes to
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primary key.
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Primary key is ah record our role that can identify
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Oh, identify the full record off person Or it will
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fetch us a complete information about a particle Aw, data
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that is primary key.
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We will discuss primary key and foreign key later when
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we are doing up practical tze that time you will
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get more used with these constraints Next foreign key foreign
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key is actually used when there are multiple tables are
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there in a database Korea.
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So there is a foreign Crimmins primary key off a
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table is used in another table as fallen chill It's
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quite confusing, But I will tell you while we are
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doing the problems again then check can stream check and
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streams means it will take the values Okay if I'm
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setting some values if I'm just like a salary salary
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minimum wages should be 6000 Hey, I'm setting that minimum
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wage You should visit.
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So I have supposed Thio enter the data into that
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column. Is it should be greater than 6000 read.
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It won't go below 6000, that is I can sit
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there. Check Can spring.
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Okay, so that's all the constraints.
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Don't bow, Be panic.
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We will learn this all in detail ing while doing
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our practical is very easy.
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Ah, nde, that's all for today's.
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Okay, so we learned about a d B m s
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ah, tables on the components.
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Then return learned constraints.
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So the task is make notes on submit on it
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on GC up.
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Yeah. Thank you.
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And have a nice day to all.
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Bye. Take care.