Learn Microsoft SQL Server SELECT And ORDER By Clauses. How to learn sql server?
Well come to Section 2 in this section we’ll be discussing about select an order by clauses two of the major causes in C will discuss how to use a bezique select clothes how to select or columns how to select some or all columns using column names in your column headings how to perform mathematical oppression how to use system functions.
We’ll also see what conditional evaluation looks like in silly clothes.We’ll see how to select top end values how to filter duplicates how to use basic order by clause. Finally we’ll discuss about exercise questions for the D.S..
How to use a basic SELECT clause?
We are back to see concert Management Studio Now if you want to follow along you should be able to find lectures to see fall in resources folder for. Let’s first see what the bezique select clause looks like. Let’s change our data is context. CIA factbook DV. Select can be used or the FROM clause to select a number or string. Or at least Trotz.
We’ll see what the FROM clause and what it’s going to help us in a cabbing sections. So look the number literally like the one you see some like 100 or any decimal point like one hundred point ninety eight. You can’t just simply type select plus the number that you want to select. Next you’ll select the query that you want to execute.
As we’ve discussed previously and you click on execute you’ll see the column being selected with 100 9 8 and no column name is available. If you want to provide a column name to little you just selected you can use is reserved for word and this is number. Now if it’s like the column heading will be this is the number and the value of the column only has one recurved.
One hundred ninety eight if you want to select a string or it takes like here it just can’t tie the string itself. It has to be called. Inside a single call. So if I execute this war you see that the string literal We need that single quarter around the text that you’re selecting the same thing goes for dates. If you only select a date literal it has to be quarter to each side a single called like the one you see here how ever if I don’t have that inside a single code sequence server simply returns 0.
How to select all columns ?
In this movie we’ll discuss how this works. All columns and rows from a table we have a fully dedicated section for of course what the FROM clause does is it’s going to help us to reference tables or a subset select statements. To rephrase that so that we can be able to carry combs in the subjects that might if you like to query all in rows and columns form a table you can simply type select stories from a table.
We have a table called country here and if we want to see all columns and all the rules from a table called country we can’t see this. However in production environment this is not recommended as a table could have a lot of rows and columns and it might slow down an hour or so. But in a development environment this will help us see what their rows and columns of a table look like.
How to select some columns using column name and display only the top n values?
In the previous Paragraph we’ve seen how we can be able to select all columns from a table for example from a country we simply did select stories from a country and we were able to see all the columns and all the rows from that table in this movie. Let’s see how we can be able to project or see only some of the columns from that table as well as how we can only be able to filter and see some of the top values of that table.
We only want to see the name of the country and its population size we can specify the column names and we can execute. Now we’re only going to be seeing these two columns on the table next. Let’s look at how we can only be able to see only the top and the values of that tape for example are here to see only the top five by use from a table called for then we can use a top function.
A function can be a top and a number or we can use a top inside Apprentice’s. Now this will become a national function that we can pass a parameter from a procedure to it. Now if I execute this one it’s going to show me only the top five values from a table Weaver.