Lists (in and not in)

The in keyword allows you to select values that match any one of a list of values. not in finds rows that do not match the values in the list.

The expression can be a constant or a column name, and the values list can be a set of constants or a subquery. Separate items following the in keyword by commas, and enclose then entire list of values in parentheses. Use single or double quotes around char, varchar, unichar, unitext, univarchar, and datetime values.

For example, to list the names and states of all authors who live in California, Indiana, or Maryland, use:

select au_lname, state 
from authors 
where state in ("CA", "IN", "MD")

 au_lname         state 
 -----------      ----- 
 White            CA 
 Green            CA 
 Carson           CA 
 O’Leary          CA 
 Straight         CA 
 Bennet           CA 
 Dull             CA 
 Gringlesby       CA 
 Locksley         CA 
 Yokomoto         CA 
 DeFrance         IN 
 Stringer         CA 
 MacFeather       CA 
 Karsen           CA 
 Panteley         MD 
 Hunter           CA 
 McBadden         CA

Using the in keyword in the query produces the same result set as the following, longer query:

select au_lname, state 
from authors 
where state = "CA" or state = "IN" or state = "MD"

Perhaps the most important use for the in keyword is in nested queries, which are also called subqueries.

For example, suppose you want to know the names of the authors who receive less than 50 percent of the total royalties on the books they coauthor. The authors table stores author names and the titleauthor table stores royalty information. By putting the two tables together using in, but without listing the two tables in the same from clause, you can extract the information you need. The following query:

Searches the titleauthor table for all au_ids of authors making less than 50 percent of the royalty on any one book.

Selects from the authors table all the author names with au_ids that match the results from the titleauthor query. The results show that several authors fall into the less than 50 percent category.

select au_lname, au_fname 
from authors 
where au_id in 
  (select au_id 
   from titleauthor 
   where royaltyper <50)

au_lname          au_fname 
--------------    ------------ 
Green             Marjorie 
O’Leary           Michael 
Gringlesby        Burt 
Yokomoto          Akiko 
MacFeather        Stearns 
Ringer            Anne 
 
(6 rows affected)

not in finds the authors that do not match the items in the list. The following query finds the names of authors who do not make less than 50 percent of the royalties on at least one book.

select au_lname, au_fname 
from authors 
where au_id not in 
  (select au_id 
   from titleauthor 
   where royaltyper <50)

au_lname          au_fname 
---------------   ------------ 
White             Johnson 
Carson            Cheryl 
Straight          Dick 
Smith             Meander 
Bennet            Abraham 
Dull              Ann 
Locksley          Chastity 
Greene            Morningstar 
Blotchet-Halls    Reginald 
del Castillo      Innes 
DeFrance          Michel 
Stringer          Dirk 
Karsen            Livia 
Panteley          Sylvia 
Hunter            Sheryl 
McBadden          Heather 
Ringer            Albert 
Smith             Gabriella
 
(18 rows affected)