Cloud Database Development and Management

214  ◾  Cloud Database Development and Management

information as the intermediate result. Based on the output of the subquery, the main query will

return the information about the classes.

Notice that you must enclose the subquery within parentheses. e = operator in the WHERE

clause is used since only a single value is returned by the subquery. Sometimes, a subquery returns

multiple values. In such a case, the IN operator should be used in the search condition. e next

example in Figure 6.33 shows that two different student ids match the last name Cox returned by

the subquery. erefore, the IN operator is used in the WHERE clause.

To select dat ...