12/3/2023 0 Comments Mysql like with multiple fields![]() ![]() We now want to find out the name of the classroom where each student played and studied. Let’s see how to join tables in SQL with three conditions. We can have even more conditions if needed. In the previous example, we saw how to join two tables by two conditions. To get more practice with joining tables in SQL, check out this interactive SQL JOINs course. Looks good! We now see the corresponding teacher's education level for each student. As you see, to specify two conditions, we simply put both of them in the ON clause using the AND keyword in between. Notice the two conditions in the ON clause as we condition on both (1) the first name from the teachers table to be equal to the teacher's first name in the students table and (2) the last name from the teachers table to be equal to the teacher's last name in the students table. If you need a refresher on the SQL JOIN syntax, check out this great SQL JOIN Cheat Sheet. ON s.teacher_first_name = t.first_name AND s.teacher_last_name = t.last_name SELECT s.first_name, s.last_name, s.teacher_first_name, s.teacher_last_name, t.education AS teacher_education As long as we don't have teachers with identical full names, we can safely join these tables by these two columns. However, we do have the teacher's first and last names in both tables. Unfortunately, we don't have the teacher ID column in the students table. For this, we need to combine the information from the tables students and teachers. In our first example, we want to know the education level of the teacher for each student. It’s time for a couple of SQL queries! Example 1: SQL JOIN by Two Columns However, even with the data stored like this, we can join the tables as long as each table has a set of columns that uniquely identifies each record. Typically, the students table would include foreign keys like the teacher ID and the class ID instead of detailed information about the corresponding teachers and classes. You might notice our database is not perfectly organized.
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