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Question
What is the process for adding a NOT NULL column to a table?Answer
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Related questions
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Suppose you have created a data model for an airline based on a variety of forms, reports, user interviews, data sources, etc. Your client comes forward with a new desired report that includes passenger weights and a relationship between passengers and employees, neither of which is in your E-R diagram. You should ________.
A) create a new, separate E-R diagram with just the new information
B) add the relationship and the weight attribute to the existing data model
C) add the relationship but not the weight attribute
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Which of the following is not true about subtype entities?
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Recursive relationships only exist for one-to-one relationships.
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All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
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ID-dependent entities are a common type of weak entity.
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An entity that represents something that can exist on its own is called a strong entity.
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In an E-R model, the three types of minimum cardinality are mandatory, optional, and indeterminate.
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In a 1:N relationship, the term parent refers to the N side of the relationship.
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Relationships are classified by their cardinality.
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In today's E-R models, attributes of relationships are still used.
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Explain denormalization, and why it may be appropriate to denormalize a set of tables.
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When accessing table structure, how do you determine how many rows are in a table?
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To check for null values in a column in a table, use the SQL phrase ________.
A) IS
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When a table is created using existing data from multiple sources, you are likely to find that the different sources code data in slightly different ways. This is an example of ________.
A) the multivalued, multicolumn problem
B) the inconsistent values problem
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A classic example of unneeded normalization is when we are dealing with ________.
A) ZIP codes
B) sales orders and line items
C) association patterns
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The SQL keyword TOP ________.
A) limits the number of columns retrieved from a table
B) limits the number of rows retrieved from a table
C) limits the number of tables retrieved from a database
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During the second step of assessing table structure, you are trying to determine ________.
A) relationships
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C) updatability
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The first step in assessing table structure includes ________.
A) counting rows
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D) Both A and B are correct
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A null value in a column may indicate that there is an appropriate value for that attribute, but it is unknown.
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An inconsistent values problem is created when different users have coded the same data entries differently.
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Creating a read-only database is a job often given to beginning database professionals.
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The SQL DELETE TABLE statement can be used to remove unneeded tables after the normalized tables are created and populated.
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The SQL INSERT statement can be used to populate normalized tables.