To remove duplicate values from PROC SQL output, you specify the DISTINCT keyword before the column name in the SELECT clause.

To list rows that have no data (that is, missing data), you can use either of these other conditional operators: IS MISSING or IS NULL. The NOT EXISTS operator is used specifically with a subquery, and resolves to true if the subquery returns no values to the outer query.

When a WHERE clause references a new column that was defined in the SELECT clause, the WHERE clause must specify the keyword CALCULATED before the column name.

To determine how PROC SQL calculates and displays output from summary functions, consider the key factors. This PROC SQL query has a GROUP BY clause, and it does not specify any columns that are outside of summary functions. Therefore, PROC SQL calculates and displays the summary function for each group. There are 7 unique values of FlightNumber, but the HAVING clause specifies only the flights that have an average number of boarded passengers greater than 150. Because 4 of the 7 flight numbers meet this condition, the output will contain 4 rows.

Your PROC SQL query needs to use data from both tables. The outer query reads the name and number of books checked out from Library.Circulation. The multiple-value noncorrelated subquery selects the names of volunteers from Library.Volunteers and passes these names back to the outer query. The outer query then selects data for only the volunteers whose names match names returned by the subquery. The subquery is indented under the outer query's WHERE clause, is enclosed in parentheses, and does not require a semicolon inside the closing parenthesis.

A noncorrelated subquery is a nested query that executes independently of the outer query. The outer query passes no values to the subquery.

The syntax in this PROC SQL query is valid, so the first statement is false. The query contains a correlated subquery, so the second statement is true. The VALIDATE keyword is used after the PROC SQL statement, so the third statement is true. And the last statement correctly indicates that the VALIDATE keyword causes the SAS log to display a special message if the query syntax is valid, or standard error messages if the syntax is not valid.

In this PROC SQL query, the outer query uses the operator NOT EXISTS with a correlated subquery. The outer query selects all rows from Charity.Donors whose names do not appear in Charity.Current. In other words, this PROC SQL query output lists all donors who did not make a contribution in the current year.

The third statement about data remerging is correct.

PROC SQL can execute this query, but the query will not produce the results that you want. If you omit the GROUP BY clause in a query that contains a HAVING clause, then the HAVING clause and any summary functions treat the entire table as one group. Without a GROUP BY clause, the HAVING clause in this example calculates the average circulation for the table as a whole (all books in the library), not for each group (each category of books). The output contains either all the rows in the table (if the average circulation for the entire table is less than 2500) or none of the rows in the table (if the average circulation for the entire table is greater than 2500).