The SQL LEFT JOIN returns all rows from the left table, even if there are no matches in the right table. This means that if the ON clause matches 0 (zero) records in the right table; the join will still return a row in the result, but with NULL in each column from the right table.
This means that a left join returns all the values from the left table, plus matched values from the right table or NULL in case of no matching join predicate.
The basic syntax of a LEFT JOIN is as follows.
SELECT table1.column1, table2.column2... FROM table1 LEFT JOIN table2 ON table1.common_field = table2.common_field;
Here, the given condition could be any given expression based on your requirement.