我正在尝试执行以下查询:

INSERT INTO table_listnames (name, address, tele)
VALUES ('Rupert', 'Somewhere', '022')
WHERE NOT EXISTS (
    SELECT name FROM table_listnames WHERE name='value'
);

但是这会返回一个错误。基本上我不想插入一个记录,如果记录的“名称”字段已经存在于另一个记录-如何检查新名称是否唯一?


当前回答

INSERT IGNORE INTO `mytable`
SET `field0` = '2',
`field1` = 12345,
`field2` = 12678;

这里的mysql查询,即插入记录,如果不存在,将忽略现有的类似记录。

----Untested----

其他回答

这个查询可以在PHP代码中使用。

我在这个表中有一个ID列,所以我需要检查除了这个ID列之外的所有列的复制:

#need to change values
SET @goodsType = 1, @sybType=5, @deviceId = asdf12345SDFasdf2345;    


INSERT INTO `devices` (`goodsTypeId`, `goodsId`, `deviceId`) #need to change tablename and columnsnames
SELECT * FROM (SELECT @goodsType, @sybType, @deviceId) AS tmp
WHERE NOT EXISTS (
    SELECT 'goodsTypeId' FROM `devices` #need to change tablename and columns names
    WHERE `goodsTypeId` = @goodsType
        AND `goodsId` = @sybType
        AND `deviceId` = @deviceId
) LIMIT 1;

现在只有在SET字符串中配置的值不存在的情况下才会添加新项

我并不是建议你这样做,因为Piskvor和其他人建议的UNIQUE索引是一个更好的方法,但你实际上可以做你正在尝试的事情:

CREATE TABLE `table_listnames` (
  `id` int(11) NOT NULL auto_increment,
  `name` varchar(255) NOT NULL,
  `address` varchar(255) NOT NULL,
  `tele` varchar(255) NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB;

插入一个记录:

INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (
    SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;

Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

SELECT * FROM `table_listnames`;

+----+--------+-----------+------+
| id | name   | address   | tele |
+----+--------+-----------+------+
|  1 | Rupert | Somewhere | 022  |
+----+--------+-----------+------+

尝试再次插入相同的记录:

INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (
    SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;

Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

+----+--------+-----------+------+
| id | name   | address   | tele |
+----+--------+-----------+------+
|  1 | Rupert | Somewhere | 022  |
+----+--------+-----------+------+

插入一条不同的记录:

INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'John', 'Doe', '022') AS tmp
WHERE NOT EXISTS (
    SELECT name FROM table_listnames WHERE name = 'John'
) LIMIT 1;

Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

SELECT * FROM `table_listnames`;

+----+--------+-----------+------+
| id | name   | address   | tele |
+----+--------+-----------+------+
|  1 | Rupert | Somewhere | 022  |
|  2 | John   | Doe       | 022  |
+----+--------+-----------+------+

等等……


更新:

为了防止#1060 -重复列名错误,如果两个值可能相等,你必须命名内部SELECT的列:

INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'Unknown' AS name, 'Unknown' AS address, '022' AS tele) AS tmp
WHERE NOT EXISTS (
    SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;

Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

SELECT * FROM `table_listnames`;

+----+---------+-----------+------+
| id | name    | address   | tele |
+----+---------+-----------+------+
|  1 | Rupert  | Somewhere | 022  |
|  2 | John    | Doe       | 022  |
|  3 | Unknown | Unknown   | 022  |
+----+---------+-----------+------+

这不是答案,只是个便条。如果插入的值是重复的,则像接受的答案中那样的查询将不起作用,就像下面这样:

INSERT INTO `addr` (`email`, `name`) 
  SELECT * FROM (SELECT 'user@domain.tld', 'user@domain.tld') AS tmp 
  WHERE NOT EXISTS (
    SELECT `email` FROM `addr` WHERE `email` LIKE 'user@domain.tld'
  );

Error
SQL query: Copy Documentation

MySQL said: Documentation

#1060 - Duplicate column name 'user@domain.tld'

相反,Mahbub Tito回答的问题很好:

INSERT INTO `addr` (`email`, `name`) 
  SELECT 'user@domain.tld', 'user@domain.tld' 
  WHERE NOT EXISTS (
    SELECT `email` FROM `addr` WHERE `email` LIKE 'user@domain.tld'
  );

1 row inserted.

在MariaDB中测试

工作:

INSERT INTO users (full_name, login, password) 
  SELECT 'Mahbub Tito','tito',SHA1('12345') FROM DUAL
WHERE NOT EXISTS 
  (SELECT login FROM users WHERE login='tito');

你可以简单地使用以下方法:

INSERT INTO ... ON DUPLICATE KEY UPDATE ...

通过这种方式,您可以插入任何新的原始数据,如果有重复的数据,则替换特定的列(最好的列是时间戳)。 例如:

CREATE TABLE IF NOT EXISTS Devices (
  id         INT(6)       NOT NULL AUTO_INCREMENT,
  unique_id  VARCHAR(100) NOT NULL PRIMARY KEY,
  created_at VARCHAR(100) NOT NULL,
  UNIQUE KEY unique_id (unique_id),
  UNIQUE KEY id (id)
)
  CHARACTER SET utf8
  COLLATE utf8_unicode_ci;

INSERT INTO Devices(unique_id, time) 
VALUES('$device_id', '$current_time') 
ON DUPLICATE KEY UPDATE time = '$current_time';