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1CREATE TABLE IF NOT EXISTS `my_table` (
2  `number` int(11) NOT NULL,
3  `name` varchar(50) NOT NULL,
4  `money` int(11) NOT NULL,
5  PRIMARY KEY (`number`,`name`)
6) ENGINE=MyISAM;
7	
8INSERT INTO `my_table` (`number`, `name`, `money`) VALUES
9(1, 'S. Name', 150), (2, 'Another Name', 284);
10	
11INSERT INTO `my_table` (`number`, `name`, `money`) VALUES
12(2, 'S. Name', 240);
13	
14#1062 - Duplicate entry '2-S. Name' for key 'PRIMARY'
15	
16DESCRIBE my_table;
17	
18DROP TABLE `my_table`; --make backup - it deletes table
19
20CREATE TABLE `my_table` (
21  `number` int(11) NOT NULL,
22  `name` varchar(50) NOT NULL,
23  `money` int(11) NOT NULL,
24  PRIMARY KEY (`number`,`name`),
25  UNIQUE (`number`, `name`) --added unique on 2 rows
26) ENGINE=MyISAM;
27	
28ALTER TABLE table ADD PRIMARY KEY(fieldA,fieldB);
29	
30#1062 Duplicate entry 'valueA-valueB' for key 'PRIMARY'
31	
32select * from table where fieldA='valueA' and fieldB='valueB'
33	
34select * from my_table
35	
36CREATE TABLE IF NOT EXISTS `my_table` (
37   `number` int(11) NOT NULL AUTO_INCREMENT,
38   `name` varchar(50) NOT NULL,
39   `money` int(11) NOT NULL,
40    PRIMARY KEY (`number`,`name`)
41) ENGINE=MyISAM;
42	
43ALTER TABLE mytbl ADD UNIQUE (columnName);