Is it possible to join 3 tables

StudentID, s. FName, s. LName, s. Gender, s. BirthDate, s. Email, r. HallPref1, r. HallPref2, r. Halls AS h ON r. Improve this question. Neuron 4, 4 4 gold badges 24 24 silver badges 46 46 bronze badges. Bob Sanders Bob Sanders 4, 4 4 gold badges 16 16 silver badges 11 11 bronze badges. Add a comment. Active Oldest Votes. StudentID , s. FName , s. LName , s. Gender , s. BirthDate , s. Email , r. HallPref1 , h1. HallPref2 , h2.

HallPref3 , h3. Halls AS h1 ON r. Halls AS h2 ON r. This is crucial because before you join multiple tables, you need to identify these tables first. For each call, we want to display what was the outcome as well the first and the last name of the employee who made that call. To do that, we need to determine which tables contain the data we need and include them.

For each country display its name in English, the name of the city customer is located in as well as the name of that customer. Return even countries without related cities and customers. We have 7 counties and 6 cities in our database, but our query returns only 4 rows. That is the result of the fact we have only 4 customers in our database. Each of these 4 is related to its city and the city is related to the country.

From the second row, we see that the student with the ID equal to 1 is connected to the course with the ID equal to 3. Then, looking at the student table, we can read that Shreya Bain has an ID equal to 1. Finally, looking at the course table, we can read that English literature and Python programming have IDs equal to 2 and 3, respectively.

The relationship between the student and course tables is called a many-to-many relationship. One student can be attending many courses i. Is the code still confusing? The first step is to look at the schema and select the columns we want to show. The next step is to determine which tables will be necessary for the query. There are two obvious ones: student and course. The first task is to choose the table which will go in the FROM clause. Our code takes shape:.

So, then, our query looks like this:. This query shows almost all the columns we can use while writing the next JOIN statement. This is how our data looks midstep. You sometimes may want to consider writing such a query from time to time just to analyze the rows and columns.

The above result should clearly show what to do next. The only thing we need is to add is course information. We have to join it with the id column from the course table.

The resulting query looks like this:. This is the most common type of JOIN. However, you can also use non-equi JOINs. Each teacher-student pair should be shown only once e.

This query is pretty similar to the previous one.