SELECT * FROM TEST ;
+------+------+------+
| A    | B    | C    |
+------+------+------+
| 1    | 2    | 3    |
| 4    | 5    | 6    |
| 7    | 8    | 9    |
+------+------+------+
3 rows in set (0.00 sec)

SELECT A FROM TEST ;
+------+
| A    |
+------+
| 1    |
| 4    |
| 7    |
+------+

SELECT * FROM TEST.A ;
ERROR 1146 (42S02): Table 'TEST.A' doesn't exist

/* SQL Error (1054): Unknown column 'TEST.A' in 'where clause' */

SELECT t1.name, t2.salary FROM employee AS t1, info AS t2 WHERE t1.name = t2.name;

use DB
Database changed
mysql> SELECT TEST.A FROM Test;
ERROR 1146 (42S02): Table 'DB.Test' doesn't exist

mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| DB                 |
+--------------------+
2 rows in set (0.00 sec)

mysql> SHOW TABLES;
+--------------+
| Tables_in_DB |
+--------------+
| TEST         |
+--------------+
1 row in set (0.00 sec)

mysql> SELECT TEST.A FROM TEST;
+------+
| A    |
+------+
| 1    |
| 4    |
| 7    |
+------+
3 rows in set (0.00 sec)

SELECT * FROM TEST.A ;
ERROR 1146 (42S02): Table 'TEST.A' doesn't exist

mysql> SELECT * FROM connections LIMIT 2;
+------------+----------+-------------+-------------+--------------+----------+
| Day        | Login    | Name        | VPN_IP      | Client_IP    | Country2 |
+------------+----------+-------------+-------------+--------------+----------+
      |06-08 | 21:38:40 | Name  Name  | 10.168.0.11 | XX.XXX.XXX.X |   
      |06-08 | 20:30:23 | Name  Name  | 10.168.0.11 | XX.XXX.XXX.X |   
+------------+----------+-------------+-------------+--------------+----------+
2 rows in set (0.00 sec)

mysql> SELECT * FROM IPs LIMIT 2;
+---------+-----------+---------+
| StartIP | EndIP     | Country |
+---------+-----------+---------+
     |0.0 | 1.0.0.255 | AU
     |1.0 | 1.0.3.255 | CN
+---------+-----------+---------+
2 rows in set (0.00 sec)

UPDATE connections SET connections.country2 = (SELECT IPs.country as country2 FROM IPs WHERE INET_ATON(connections.Client_IP) >= INET_ATON(IPs.StartIP) AND INET_ATON(connections.Client_IP) <= INET_ATON(IPs.EndIP) ) WHERE Client_IP=Client_IP AND COUNTRY2 = "";

ERROR 1242 (21000): Subquery returns more than 1 row

SELECT Country FROM `IPs` WHERE INET_ATON("192.168.10.1") >= INET_ATON(StartIP) AND INET_ATON("192.168.10.1") <=  INET_ATON(EndIp);

SELECT Country FROM `IPs` WHERE INET_ATON(connections.Client_IP) >= INET_ATON(StartIP) AND INET_ATON(connections.Client_IP) <=  INET_ATON(EndIp);
/* SQL Error (1054): Unknown column 'connections.Client_IP' in 'where clause' */
/* Affected rows: 0  Found rows: 0  Warnings: 0  Duration for 0 of 1 query: 0,000 sec. */

mysql> SHOW COLUMNS from connections;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Day       | date         | NO   |     | NULL    |       |
| Login     | time         | NO   |     | NULL    |       |
| Name      | varchar(30)  | NO   |     | NULL    |       |
| VPN_IP    | varchar(15)  | NO   |     | NULL    |       |
| Client_IP | varchar(15)  | NO   |     | NULL    |       |
| Country2  | varchar(255) | NO   |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+
6 rows in set (0.00 sec)