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Cross joins ; Inner joins ; Left outer joins ; Right outer joins ; Full outer joins ; Join conditions; Available join algorithms. Nested loop join algorithm; Block hash join. In SQL, the left join returns all the records from first table and matched records from second table.

If there is no match from second table then only records from . Different joins available in SQL are explained -- inner, left , right, and cross joins. Aliasing can be of great use when working with JOINs , and it is covered here. This example illustrates use of LEFT JOIN action.

This query retrieves all event names and places where they happen. In particular, the LEFT part means that all rows from the left table will be returne even if there's no . The LEFT JOIN is used to return data from multiple tables. Spring naar What are inner, outer, left and right merges?

Left Merge Left outer join – (aka left merge or left join ) Keep every row in the left dataframe.