Using OUTER , WHERE or Simply JOIN

Question:
Does it make a difference in placing an OUTER or simply a JOIN or a WHERE?

Using WHERE:

select tb01_field01,tbl01_field02    from tb01,tb02      where tb01_field01 = tb02_field01

Using JOIN:

SELECT TB01_FIELD01,TB01_FIELD02      FROM TB01      JOIN TB02      ON TB01_FIELD01 = TB02_FIELD01

How do I use OUTER to do the same thing as the commands above? Is it faster with OUTER?

Answer:
Your second instance, “Using JOIN”, is not valid SQL in Informix. It should be:

SELECT TB01_FIELD01,TB01_FIELD02      FROM TB01, TB02      WHERE TB01_FIELD01 = TB02_FIELD01

The OUTER statement only deals with what happens when one of the tables has rows that are not matched by the JOIN. It is probably a little slower than a regular JOIN, because it has to include rows that would not be returned in a non-OUTER join.

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