This is another very valuable topic that I wanted to share with you. I think I mentioned this, I said there's a possibility that you'll need to update multiple rows. And in this instance and in this example I'm showing you that I have an employees table and in this table I have four columns. The empid, the last name, the first name and the email. And what I have not shown you here is having you assume that email is left empty and that you want to fill in the email address after the fact you added the email column after all of the data in these three columns was filled in. The reason for that is because the email address followed a particular formula if you will, in the email address was a combination of a last name, period, first name@company.com. So in order to do that, in order to issue an update command so that the email address could be filled in. It happens something like this, you really just say update employees which is the name of the table. So you're updating the employees table, that's the employees table. And you're setting the email. Email is this column right here, setting is that's really what you want to impact your setting the email to be the lower, lower is lower case. In other words, if the last name and first name contains upper letters in this case J and A are in upper case, lower is going to turn all of the text to lowercase, that's the purpose of that. So the email will be the lower of the last name that is combined with or can concatenated with those pipes concatenate. They essentially take the last name value from the last name field and they add the period, right? And then they add the first name value and then they add or concatenate the @company.com. Notice those are in quotes are, the reason they're in quotes is because our single quotes is because it's all text. Okay, the period is text and so is the @company.com for example. Okay, so the email address will be filled in as follows given this last and first name. And since there's no where clause specified here, since there is no where clause specified here, it would essentially change the email address of all rose to be the last name and first name in that row with that format. Let me show you what I'm talking about so you can see how this works. So here I have the employee table, there's the empid, last name, first name and email. Right now it's all empty, here's a construction. I'm automatically populating the empid with a pre-generated identity is going to be 1234 and so on. So here's what I'm going to do, I'm going to do insert into and I'm going to say the I'm going to insert into the employees table, employees table. And I'm going to insert the last name and the first name columns, not the address column, not the email column. And I'm going to say the values I'm going to insert will be will be Johnson,adam like so. When I run this, it ran it. So I'm going to insert the next name and I'm going to add in Williams and Jane, run that. And I'm going to add in one name, Amanda Harrison. There you go. Now when I run this, when I look at the table, notice the email address is blank. In all instances I've got Adam, Jane and Amanda. So the way to populate that is about doing this, I'm going to do update employees set email and I'm going to say is equal to the lower last name. Concatenate that with a period. Concatenate that with the first name. Concatenate that with company.com. Run that, done. Notice how It says three rows inserted, you see that updated, not inserted but updated. Now when I run this, look, there's a last name.first name@company.com. So in this instance I updated every row with that format of an email. Okay, So I just wanted to show you how this works. So you saw firsthand how you can sort of update all of the roads and why you would want to update all of the roads on the table without providing the where clause for a filter criteria. Yeah.
