What Are the Four Different Types of Results That Can

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The Answer is A 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.

What Are the Four Different Types of Results That Can

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