This post has explained the usage of the INNER JOIN in PostgreSQL using practical examples.In this section, we are going to understand the working of several types of PostgreSQL joins, such as Inner join, Left join, Right join, and Full Outer join in brief. If the tables to be joined have the same column names, then the “USING” clause can be used instead of the “ON” clause to define a join condition. The “ON” clause is used with the INNER JOIN to define a joining condition. In PostgreSQL, the INNER JOIN is used to get the matching results from two or more tables based on a specific join condition. The output authenticates that the “emp_bio”, “dpt_info”, and “emp_details'' tables have been successfully joined. While the second INNER JOIN is used to join the emp_info table with the other two tables based on the “dpt_id”: In the above code, the first INNER JOIN is used to join the “emp_bio” and “emp_details” tables on the basis of “e_id”. Let’s learn how to join three tables using the INNER JOIN: SELECT emp_bio.e_name, emp_bio.emp_name, In the “emp_details” table, the “e_id” and “dpt_id” are foreign keys. The third sample table is “emp_details”, whose details are enlisted in the following snippet: SELECT * FROM emp_details In the “dpt_info” table, “dpt_id” is a primary key. Let’s execute the “SELECT” command one more time to fetch the results from the “dpt_info” table: SELECT * FROM dpt_info In the “emp_bio” table, “e_id” is a primary key. Let’s utilize the SELECT query to fetch the details of each table: SELECT * FROM emp_bio All these tables are linked with each other via the foreign key constraint. Suppose we have three tables: “emp_bio”, “dpt_info”, and “emp_details''. The “employee_information” and “department_information” tables have been joined successfully using the “INNER JOIN”.Įxample 3: Joining Three Tables Using the INNER JOIN Here, the column name “e_id” is the same in both tables, so the given tables can be joined using the INNER JOIN and the USING clause: However, in such a case the column names should be the same in both tables: SELECT employee_information.e_id, The “USING” clause can also be used along with the “INNER JOIN” to join/combine multiple tables. The output snippet validates that the given tables have been successfully joined using the “INNER JOIN”. ON employee_information.e_id = department_information.e_id Let’s use the INNER JOIN to join the “employee_information” and “department_information” tables based on the “e_id”: SELECT employee_information.e_id,

The “e_id” is a primary key in the “employee_information” table and the foreign key in the “department_information” table. Use the “SELECT *” command to get the detailed information regarding the “department_information” table: SELECT * FROM department_information

We have already created a couple of sample tables, whose details are depicted in the following snippets: SELECT * FROM employee_information Here, the “INNER JOIN” will join the selected tables based on the condition defined via the “USING” clause. If the tables to be joined have the same column names, then the “USING” clause can be used instead of the “ON” clause to define a join condition: SELECT col_list The “ON” clause defines the joining condition. The “INNER JOIN” joins the given tables according to the specified JOIN condition. The tables’ columns will be specified as “table_l_name”, i.e., “tab_1.col_name”, and “tab_2.col_name”. “tab_1” and “tab_2” are the tables to be joined. Use the below syntax to combine multiple tables using “INNER JOIN”: SELECT, In Postgres, the INNER JOIN is used to get the matching results from two or more tables based on a specific join condition. This post will specifically discuss the usage of the Postgres INNER JOIN using suitable examples. PostgreSQL supports various types of JOINS, such as “ INNER JOIN”, “ OUTER JOIN”, “ NATURAL JOIN”, “ SELF JOIN”, etc. For this purpose, the Joins are used in databases. To get detailed information, you might need to combine/merge the data of various tables. In relational databases, data is distributed into various tables. PostgreSQL is a renowned freely available relational database.

Postgres join types