In which two cases would you use an outer join? (choose two.) a. the columns being joined have null values. b. the tables being joined have both matched and unmatched data. c. the tables being joined have not null columns. d. the tables being joined have only matched data.
according to me the answer should be B and C
but not sure
The column being joined will have null value and also the table joined have matched and unmatched data have an outer join.
Option A and Option B are the two cases to use an outer join.
OUTER JOIN is utilized for returning data from all rows from both the joined tables that satisfy JOIN condition and return all data from the rows which does not satisfy the same JOIN condition.
The OUTER JOIN should be used utilized within the JOIN condition only. As, in some cases, some of the columns might have null values. In that case, also, OUTER JOIN can be utilized. The joined fields alone should be the same so that it will join the table with both the matched and unmatched data.
the tables to be joined have columns of the same name and different data types.
the tables to be joined have multiple null columns.
Explanation:When more than one column matches or combined Using clause is used to match one. The two complete clauses are mostly using clause and Natural join. The using clause chooses or indicates which column or options should be testes for quality when comparing two things. The Natural join consumes all the columns with similar names and datatypes to combine the tables.
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telephone book is the answer of first