The COUNT function

The following query counts and displays the total number of rows in the stock table.

Figure 1. Query

SELECT COUNT(*) FROM stock;

Figure 2. Query result

(count(*))

   73

The following query includes a WHERE clause to count specific rows in the stock table, in this case, only those rows that have a manu_code of SHM.

Figure 3. Query

SELECT COUNT (*) FROM stock WHERE manu_code = 'SHM';

Figure 4. Query result

(count(*))

   17

By including the keyword DISTINCT (or its synonym UNIQUE) and a column name in the following query, you can tally the number of different manufacturer codes in the stock table.

Figure 5. Query

SELECT COUNT (DISTINCT manu_code) FROM stock;

Figure 6. Query result

(count)

   9