(See related pages)
This chapter extends your query formulation skills by explaining advanced table matching problems involving the outer join, difference, and division operators. Other parts of the SELECT statement are demonstrated to explain these advanced matching problems. In addition, the subtle effects of null values are explained to help you interpret query results involving null values. After this chapter, you should have acquired the following knowledge and skills:
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Recognize Type I nested queries for joins and understand the associated conceptual evaluation process. |
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Recognize Type II nested queries and understand the associated conceptual evaluation process. |
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Recognize problems involving the outer join, difference, and division operators. |
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Adapt example SQL statements to matching problems involving the outer join, difference, and division operators. |
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Understand the effect of null values on conditions, aggregate calculations, and grouping. |