1/21/2024 0 Comments Postgres outer joinHowever, you will notice that the supplier_name field for that record contains a value.Īnother type of join is called a PostgreSQL FULL OUTER JOIN. The row for 500127 (order_id) would be included because a RIGHT OUTER JOIN was used. Our result set would look like this: order_id If we run the SELECT statement (that contains a RIGHT OUTER JOIN) below: SELECT orders.order_id, orders.order_date, suppliers.supplier_name Let's look at some data to explain how RIGHT OUTER JOINS work: If a supplier_id value in the orders table does not exist in the suppliers table, all fields in the suppliers table will display as in the result set. This RIGHT OUTER JOIN example would return all rows from the orders table and only those rows from the suppliers table where the joined fields are equal. Here is an example of a PostgreSQL RIGHT OUTER JOIN: SELECT orders.order_id, orders.order_date, suppliers.supplier_name The PostgreSQL RIGHT OUTER JOIN would return the all records from table2 and only those records from table1 that intersect with table2. In this visual diagram, the PostgreSQL RIGHT OUTER JOIN returns the shaded area: The syntax for the PostgreSQL RIGHT OUTER JOIN is: SELECT columns This type of join returns all rows from the RIGHT-hand table specified in the ON condition and only those rows from the other table where the joined fields are equal (join condition is met). However, you will notice that the order_date field for those records contains a value.Īnother type of join is called a PostgreSQL RIGHT OUTER JOIN. ![]() The rows for Microsoft and NVIDIA would be included because a LEFT OUTER JOIN was used. If we run the SELECT statement (that contains a LEFT OUTER JOIN) below: SELECT suppliers.supplier_id, suppliers.supplier_name, orders.order_date ![]() We have a second table called orders with three fields (order_id, supplier_id, and order_date). Let's look at some data to explain how LEFT OUTER JOINS work: If a supplier_id value in the suppliers table does not exist in the orders table, all fields in the orders table will display as in the result set. This LEFT OUTER JOIN example would return all rows from the suppliers table and only those rows from the orders table where the joined fields are equal. Here is an example of a PostgreSQL LEFT OUTER JOIN: SELECT suppliers.supplier_id, suppliers.supplier_name, orders.order_date The PostgreSQL LEFT OUTER JOIN would return the all records from table1 and only those records from table2 that intersect with table1. In this visual diagram, the PostgreSQL LEFT OUTER JOIN returns the shaded area: The syntax for the PostgreSQL LEFT OUTER JOIN is: SELECT columns This type of join returns all rows from the LEFT-hand table specified in the ON condition and only those rows from the other table where the joined fields are equal (join condition is met). WHERE suppliers.supplier_id = orders.supplier_id Īnother type of join is called a PostgreSQL LEFT OUTER JOIN. Old SyntaxĪs a final note, it is worth mentioning that the PostgreSQL INNER JOIN example above could be rewritten using the older implicit syntax as follows (but we still recommend using the INNER JOIN keyword syntax): SELECT suppliers.supplier_id, suppliers.supplier_name, orders.order_date The row for 500127 (order_id) from the orders table would be omitted, since the supplier_id 10004 does not exist in the suppliers table. The rows for Microsoft and NVIDIA from the supplier table would be omitted, since the supplier_id's 1003 do not exist in both tables. Our result set would look like this: supplier_id If we run the PostgreSQL SELECT statement (that contains an INNER JOIN) below: SELECT suppliers.supplier_id, suppliers.supplier_name, orders.order_date We have another table called orders with three fields (order_id, supplier_id, and order_date). It contains the following data: supplier_id We have a table called suppliers with two fields (supplier_id and supplier_name). Let's look at some data to explain how the INNER JOINS work: ![]() This PostgreSQL INNER JOIN example would return all rows from the suppliers and orders tables where there is a matching supplier_id value in both the suppliers and orders tables. ON suppliers.supplier_id = orders.supplier_id Here is an example of a PostgreSQL INNER JOIN: SELECT suppliers.supplier_id, suppliers.supplier_name, orders.order_date The PostgreSQL INNER JOIN would return the records where table1 and table2 intersect. In this visual diagram, the PostgreSQL INNER JOIN returns the shaded area: The syntax for the INNER JOIN in PostgreSQL is: SELECT columns PostgreSQL INNER JOINS return all rows from multiple tables where the join condition is met. Chances are, you've already written a statement that uses a PostgreSQL INNER JOIN.
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