JOINs in MySQL and Other Relational Databases
eduguru 0 Comments course.name FROM `user` INNER JOIN `course` on user.course = course.id; LEFT JOIN SQL LEFT JOIN What if we require a list of all students and their courses even if they’re not enrolled on one? A LEFT , course.name FROM `user` LEFT JOIN `course` on user.course = course.id UNION SELECT user.name, course.name FROM `user` LEFT JOIN `course` on user.course = course.id; RIGHT JOIN SQL RIGHT JOIN Perhaps we require a list all courses and students even if no one has been enrolled? A RIGHT JOIN produ, course.name FROM `user` RIGHT JOIN `course` on user.course = course.id;, course.name FROM `user` RIGHT JOIN `course` on user.course = course.id; OUTER JOIN (or FULL OUTER JOIN) SQL FULL OUTER JOIN Our last option is the OUTER JOIN which returns all records in both tables r, different types of joins in sql, e.g. SELECT user.name, i.e. all users who are enrolled on a course: SELECT user.name, INNER JOIN (or just JOIN) SQL INNER JOIN The most frequently used clause is INNER JOIN. This produces a set of records which match in both the user and course tables, JOINs in MySQL and Other Relational Databases, LEFT or RIGHT and it’s not implemented in MySQL. However, mysql database joins, the missing side will contain NULL. OUTER JOIN is less useful than INNER, what is joins in database, you can work around this restriction using the UNION of a LEFT and RIGHT JOIN
INNER JOIN (or just JOIN) The most frequently used clause is INNER JOIN. This produces a set of records which
Read more