From the perspective of learning. There are few things that I haven't told you yet. Kind of been saving it for this. There's some database terms you need to know about. Some things you know because I did tell you, talk to you about it. For example, ACID. ACID stands for Atomic, Consistent, Isolated, and Durable. It refers to transactions. Transactions are one or more logical units of work that are performed together. When you go to your ATM to get some cash out, for example, you are performing a transaction. And the reason it's called a transaction is because the bank, or the ATM machine, is checking your account, checking your PIN, checking to see if you have any money that you want to be able to take out. All of those things are put together into a transaction, and the name of that transaction, for example, would be withdrawal. The simple withdrawal transaction Performs many logical tasks. Validating your PIN, validating your account, validating to make sure you have money. validating to make sure that you're able to take out the money that you're requesting that is not going over your limit and so on. ACID, Atomic, Consistent, Isolated, and Durable. ADF stands for Application Development Framework. When somebody says ADF, they're talking about the underlying ability of the database engine or the framework in which you are developing such as JAVA, such as .NET, to be able to integrate with the database. It really refers to the modules and components and functions that allow that application development framework to connect to and communicate with the database. Aggregation, this is really the act of grouping many records into smaller number of records. So if you want to take line-by-line item of sales, and you want to group them together into one sun, you'd be able to do it this way. Instead of taking every single item that you have sold, you just want to know how much have you sold in the entire table structure. So this sum is an aggregate function, and it says I'm going to group the total sales by product ID. So if I had multiple products I sold, let's say five or six, I would get the total sales amount by the products. It would tell me this is how many cars I sold, this is how many warranties I sold, this is how many tires I sold, and so on, if those happen to be products. But it would sum them by total sales and group them by product ID. In this case, the aggregation is done for total sales, the column, and it is aggregated by product ID. This may yield five or six values, one for each product ID instead of giving you individual line item of sales by each product. I may have sold 100 cars. I don't want to know 100 cars I sold, I just want to know that I sold $1 million dollars in cars, and then maybe break it down by brand. Maybe say that I sold this many Ford, this many GM, this many Chryslers, this many Chevys and so on. Aggregation. Then, there's alias. Alias is a temporary name. It's actually a temporary name assignment for a column or a table. So here, for example, I've got a, see to select a dot? Select b dot. That a right here is the alias in this particular case for table called prodsales. This b right over here is an alias for a table called product. It's easier for me to say b dot and a dot, or reference the product table, by just saying b, reference the prodsales table by just saying a, if I do it this way. So this b in this case, and this a in this instance, are aliases for the prodsales and the products table, respectively. This cost, this is the actual name of the column in the prodsales table. So instead of saying cost, I'm going to display the column name is going to be sale price. So it's not going to say a dot cost, it'll say sale price, which is friendlier. So sale price, in this instance, is an alias for the cost column. Product name is an alias for prod underscore desk column in the b table or the product table, which is the b table. So product name is the alias for the prod underscore desk column. I don't want to column that's called b dot prod underscore desk. I'd rather see product name and I'd rather see sale price. It's easier to understand and it looks better. Alias.
