| Код |
mysql> create table test (id int);
Query OK, 0 rows affected (0.05 sec)
mysql> insert into test values (1),(null),(2),(null),(3);
Query OK, 5 rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from test;
+------+
| id |
+------+
| 1 |
| NULL |
| 2 |
| NULL |
| 3 |
+------+
5 rows in set (0.00 sec)
mysql> select count(*) from test;
+----------+
| count(*) |
+----------+
| 5 |
+----------+
1 row in set (0.00 sec)
mysql> select count(id) from test;
+-----------+
| count(id) |
+-----------+
| 3 |
+-----------+
1 row in set (0.00 sec)
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