![]() ![]() classes, where we have information about each class, such as the name of the kindergarten, the class, the graduation year, and the name of the classroom.teachers, where we have the name and the education level of each teacher.students, where we have information about each student, such as the name, the kindergarten he or she attended, the class, the graduation year, and the teacher.In our database, we have the following tables: Let’s imagine we run a network of kindergartens. Let’s see some examples to understand how this works in practice. The explanations are based on real-world examples that resemble problems you'll meet daily. It contains over 90 exercises that cover different JOIN topics: joining multiple tables, joining by multiple columns, different JOIN types ( LEFT JOIN, RIGHT JOIN, FULL JOIN), or joining table with itself. The best way to practice SQL JOINs is our interactive SQL JOINs course. In situations like these, you may need to use multiple columns to join tables – e.g., the first and the last names, or the order number and the year if the order numbering restarts each year. Or the tables you want to join may not have just one common column to use for joining. For example, you may encounter cases in which there is no one column in the table that uniquely identifies the rows. Joining tables by just one column does not work in some scenarios. In this article, I’ll discuss why you would want to join tables by multiple columns and how to do this in SQL. However, it is also often the case that you need to join tables by two or more columns. Most often, you’ll be joining tables based on a primary key from one table and a foreign key from another table. If you found this tutorial helpful then don't forget to share.The SQL JOIN is an important tool for combining information from several tables. ![]() This saves time on the programming side where you add the column values separately. You can specify your own separator values like – space, comma, dash, etc in the function. This functions generally use when you have to show multiple column values within a single string. Output id username firstname lastname 2 sonarika Sonarika Bhadoria WHERE CONCAT_WS(" ",firstname,lastname) = "Sonarika Bhadoria" You can use both of them in WHERE CLAUSE for selection based on condition. )ĬONCAT_WS( " ", firstname, lastname ) AS fullnameĪs I said at the start of the function you can define any other characters instead of space. Syntax – CONCAT_WS( SEPERATOR, column1, column2. It also let you define separator ( ” “, ”, “, ” – “,” _ “, etc.). The CONCAT_WS() function not only adds multiple string values and makes them a single string value. Output id username fullname 1 yssyogesh Yogesh Singh 2 sonarika Sonarika Bhadoria 3 vishal Vishal Sahu SELECTĬONCAT( firstname, " ", lastname ) AS fullname ![]() ![]() I am using this function to concatenate firstname, lastname columns and set it ALIAS to fullname. id username firstname lastname 1 yssyogesh Yogesh Singh 2 sonarika Sonarika Bhadoria 3 vishal Vishal Sahu Arguments are separated by a comma.įor demonstration, I am using Users Table which has the following records. This function is used to concatenate multiple columns or strings into a single one. In this case, you can use MySQL functions to combine the values of the columns.īoth functions work similarly but have little difference. You have two columns – firstname, lastname within your DataBase Table you want to show both the columns values in a single string form. ![]()
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