Chat with AIExam 7: Introduction to Structured Query Language Sql
The SQL command that allows a user to permanently save data changes is _____.
(29) 
VerifiedC
What are the four different types of results that can be returned from a subquery?
(37) VerifiedA subquery can return one or more values.
One single value (one column and one row):
This subquery is used anywhere a single value is expected, as in the right side of a comparison expression.An example is the preceding UPDATE subquery, in which an average price is assigned to the product's price.When a value is assigned to an attribute, a single value is assigned and not a list of them.Therefore, the subquery must return only one value (one column, one row).If the query returns multiple values, the DBMS generates an error.
A list of values (one column and multiple rows):
This type of subquery is used anywhere a list of values is expected, such as when using the IN clause-for example, when comparing the vendor code to a list of vendors.Again, in this case, there is only one column of data with multiple value instances.This type of subquery is used frequently in combination with the IN operator in a WHERE conditional expression.
A virtual table (multicolumn, multirow set of values):
This type of subquery can be used anywhere a table is expected, such as when using the FROM clause.
The fourth result that a subquery can return is no value at all.It is called NULL.
A(n) _____ join performs a relational product (also known as the Cartesian product) of two tables.
(43) VerifiedB
The _____ clause of the GROUP BY statement operates very much like the WHERE clause in the SELECT statement.
(34) The _____ command restricts the selection of grouped rows based on a condition.
(39) 
The _____ operator could be used in place of INTERSECT if the DBMS does not support it.
(34) SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT.
(29) The _____ function returns the current system date in MS Access.
(39) The _____ specification is used to avoid having duplicated values in a column.
(36) A(n) _____ is a query that is embedded (or nested) inside another query.
(40) A(n) _____ is an alternate name given to a column or table in any SQL statement.
(34) You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output.
(25) According to the rules of precedence, which of the following computations should be completed first?
(27) The _____statement in SQL combines rows from two queries and returns only the rows that appear in the first set but not in the second.
(38) The SQL aggregate function that gives the number of rows containing non-null values for a given column is _____.
(42) An alias is especially useful when a table must be joined to itself in a(n) _____ query.
(42) 
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