Exam 2: The Relational : Introduction, QBE, and Relational Algebra

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​Provide a definition for the term relation.

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A relation is a two-dimensional table in which:
1.The entries in the table are single-valued; that is,each location in the table contains a single entry.
2.Each column has a distinct name
3.All values in a column are values of the same attributes
4.The order of columns is immaterial
5.Each row is distinct
6.The order of rows is immaterial

​A query is a question represented in a way that the DBMS can recognize and process.

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The field on which records are sorted is called the ____________________.​

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​A(n)____________________ field is a field that is the result of a calculation using one or more existing fields.

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The product of two tables is also called the ____ product.​

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The comparison operators are +,*,%,and /.​

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Count,Sum,Avg,Max,and Min are a few of the built-in statistics or ____ functions that can be used in a query.​

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If you are sorting records by more than one field,the more important field is called the ____.​

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An unnormalized relation is a table that has more than one row.​

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The ____ operation is performed by the SUBTRACT command in relational algebra.​

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To list the records in a query's results in a particular order,you need to ____________________ the records.​

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A query that changes data is a(n)____ query.​

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The ____ operator is used to concatenate every row in the first table with every row in the second table.​

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____________________ is a theoretical way of manipulating a relational database.

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The ____ command within relational algebra includes the word OVER followed by a list of the columns to be included.​

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​What is the difference between an AND criterion and an OR criterion? How is each criterion created in QBE?

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The ____ key of a table is the column or collection of columns that uniquely identifies a given row in that table.​

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List at least six of the aggregate functions available in Access.Explain how to use any of these functions in a query.​

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Access automatically adds double quotation marks around values in the design grid that are formatted as Short Text fields when you run the query or move the insertion point to another cell in the design grid.​

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Columns in a table are often called ____________________.​

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