This can also be written by using implicit JOIN, $query = SELECT a.links_name, b.tag_name FROM tbl_links a, tbl_tags b WHERE a.links_category = b. The inner join query is, $query = SELECT a.links_name, b.tag_name FROM tbl_links a INNER JOIN tbl_tags b ON a.links_category = b.tag_id The query checks if the join condition is satisfied and gives intersected data as shown in the Venn diagram.

The frequently used clause in JOIN operations is ON. The major JOIN types include Inner, Left Outer, Right Outer, Cross JOINS etc. I wrote the join condition to check the mapping between the tables with the use of the columns tbl_links.links_category and the tbl_tag.tag_id having common data. The unmatched rows are returned with the NULL keyword. Using inner join, I combine the two tables tbl_links and tbl_tags to read the data from both tables. Joins in MySQL only allow you to utilize a single JOIN query instead of running multiple simple queries. I have used these common column key indexes in the below examples of MySQL JOINs. I have referred to this column as a foreign key index of the tbl_links table. This column is used to map each link data with the corresponding tag by referring to the tag_id. The structure and the data of these tables are shown below. The tbl_links table has a column named links_category. In the resultant structure, it contains data for the left side table columns if match found or NULL otherwise. Right JOIN is used to fetch all the records from the right side table. In the resultant structure, it contains data for the right side table columns if match found or NULL otherwise. Left JOIN is used to fetch all the records from the left table. The resultant table will state NULL wherever the JOIN condition is not matched. Demo Database In this tutorial we will use the well-known Northwind sample database. Self Join Syntax SELECT columnname (s) FROM table1 T1, table1 T2 WHERE condition T1 and T2 are different table aliases for the same table. Query with this type of JOIN is used to all the records from the tables. MySQL Self Join A self join is a regular join, but the table is joined with itself.

You wouldnt create a relational database if you couldnt join them and see the desired output.

It is used to get the intersected set of data from the tables based on the JOIN condition. Joins concept sits in the heart of relational database idea. This type of JOIN is the most common type. The USING ( joincolumnlist) clause names a list of columns that must exist in both tables. I have added an example for the Inner JOIN to get the joined result from the tables tbl_links and tbl_tags. In this tutorial, we are going to see the types of MySQL JOINs and a basic introduction to each type. The join conditions are written based on the common column name, data or indexes of the tables. While joining MySQL tables, we need to specify the condition for the JOIN query with the use of the ON or USING clause. MySQL JOINs are used to read data by connecting two or more related tables.

Mysql join