数据库连接
LEFT OUTER JOIN—This returns all the rows from the table on the left side of the join, along with the values from the right-hand side, or nulls if a matching row doesn't exist.
RIGHT OUTER JOIN—This returns all the rows from the table on the right side of the join, along with the values from the left-hand side, or nulls if a matching row doesn't exist.
FULL OUTER JOIN—This returns all rows from both tables, filling in any blanks with nulls. There is no equivalent for this in Oracle8i.