如何确保mysql表中没有重复项？

Question

Suppose I have 2 fields: first_name and last_name .

It is ok to have first name duplicate, or last name duplicate, but, if both first_name and last_name are the same, do not insert! It's like 2 unique keys, linked.

Answer 1

在合并的字段上创建唯一索引：

ALTER `mytable` ADD UNIQUE (`first_name`,`last_name`);

Answer 2

如果该表已经存在，则可以对其进行更改以添加一个复合唯一键：

ALTER `table_name` ADD UNIQUE (`first_name`,`last_name`);

Answer 3

All you need is an index which combines both fields. Here's a sample table definition:

CREATE TABLE IF NOT EXISTS `people` (
  `first` varchar(30) NOT NULL,
  `last` varchar(30) NOT NULL,
  UNIQUE KEY `myIndex` (`first`,`last`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Answer 4

You can do that by adding a unique constraint:

CREATE TABLE People
(
  First_Name VARCHAR(32),
  Last_Name VARCHAR(32),
  UNIQUE (First_name, Last_Name)
);

Answer 5

您只需要向表中添加一个由以下两个字段组成的唯一索引：

ALTER TABLE `your_table` ADD UNIQUE `uniq_name` ( `First_name` , `Last_name` )