 So students, now we know that we have to have a database and tables and the different model and approaches. Now in this module, I will talk about that how do we create and set up a database? Okay, how do we populate that database, right? And then what are the different data types, specific data types, for example, with reference to the time and date, and then this very interesting data type, which is the timestamp. What timestamp does it automatically okay, it automatically stores the date and time of the event. And that of course is very helpful when we would like to know what happened at what time. So let's first look at the module coverage over here. So setting up the database and the binary attribution coalitions means that what will be the precedence, okay, of processing a character. I will give you the example and of course you will understand. For example, a comes before B. But what if there is the capitalization of the characters, I will talk about it. Then is the unique constraint, unique constraint means that non repeating rows must only be shown only once row from a table. The unknown data type unknown data type is that what are the values from which a selection can be made. There are many, many benefits of this approach. So I'll talk about it. And of course the timestamp data type, which which I have told you which automatically records the time and the date of the event. Let's go into more details. So let's see how the things are going to be working over here. So we first of all set the my set the database, the my database, this has already been created. Okay, this is already been created. Now we create the table, the table for the members. And we have so idea of the member, which is auto increment, it means that you don't have to give the new idea every time. Okay, then you have this bar chart, which we have discussed binary, which we'll be discussing. And there's special data type, which is the password, first name, last name, we'll go through all of them. Okay, so we have this members table. And we have this access log. We are looking at that soccer example. Okay, we are looking at the soccer example, which we discussed before. So we have this member ID and page URL. I'll talk about what it means. Okay, and this is for that soccer and this is about this other example also. And this last access of the URL. So now we start inserting into this database, insert into members word parkey. Okay, and then look at their interest over here. And then we about this member Mary, and so on this, of course, you look at this password is not being shown. The password is not being shown. Okay, and then the interest of the members. Okay, so you see, then you are inserting, right? And this is the into the access log. These things are going to the access log. So this is how we are going to populate our database. I believe things should be clear now how the database is going to be populated. So binary attribute and coalition case in sensitivity of the coalition, it means that capital A and capital B and A and B, if you compare them together, they are going to be treated same with the coalition. But when we put the binary with it, then there is no case in sensitivity with without with with insensitivity. This is going to be the sequence a B and then the capital. But once we use the binary, then we know that first is the lower case, and then is the capital. So you see that they are different. They are they are not the same. They are not the same. Okay, I believe you understand this, you have to actually run this and enter this, and then you will understand. Then of course, if you have, if there is no case in sensitivity, and there's a person with the username john, that person can also log in with the capital J with the capital J versus which which which are not the same. They're not the same. Right. But when there's case in sensitivity, the user can log in with the capital J username and a lower case, J username also, and they will think that maybe they have two accounts. So over here we have to ensure that they are case sensitive. All right. And is the unique constraint. Okay, unique constraint means if you look at these two are the same. These two are the same. Right. Unique means of course, the contents of that column are going to be unique. But the unique is not primary because unique key can be with the null. But the primary key cannot be a null. There can be multiple columns with unique values. Right. But there can be only one column is the primary key. Because of the primary key, we are going to access and retrieve the data quickly. Okay. And the examples could be username, the user names are unique. And people are not allowed to have the same username. Email addresses are also unique. These are the examples of unique. Okay. But these are not the primary key. Primary key can be ID. Okay. A certain user ID, which is usually numeric also. It's also numeric, because the numeric processing is fast. We are looking at the performance also. And then is the enum data type with the enum data type. What we have is that we have a variety of values, a variety of values. And only among those values, a value can be selected. For example, the gender can be either male or female. The favorite junior, which is for the movie, which is for the movie data movie database. Okay, we can have a romantic movie science fiction and so on. So the benefit of the enum approach is data validation. Only either this can be selected or this can be selected or this no other value can be selected. This is for the validation. And it saves space also how it saves space. Instead of storing the horror, junior, or the romance or the three little, maybe over here, number seven is stored, maybe over here, number nine is stored. So that takes care of the space, tremendous saving of space. But remember that if theoretically over here, we can have 65,000 enum values, but usually after 20 values, it becomes very difficult. It becomes unwieldy. All right. So finally, the time, the timestamp data type, the, the time can be stored as, as recording. Okay, but over here, we look at a timestamp. This is this all is automatic. This is automatic. Okay, and it stores the event tracking the actions. There is some issue also over here, over here, that it uses this you, which it uses that format to store the time, which is similar to GMT. Right. So there's no big issue. But when the server changes that time storage format, then the data which was stored using the timestamp earlier, that may not give correct results. So you have to be careful about these issues. You should be aware of these issues, right or not?