MySQL avoids repeated insert recording methods

When doing web site development, sometimes you need to restrict certain fields, and then return to the following requirements

When a field in the database is unique, when the same data is inserted again, the update operation

Syntax: REPLACE into tablename (column) values (values)

Let's take a look at some examples

1. Create a table

Mysql>create table T1 (id int primary KEY auto_increment,

Name varchar (32)

);

2. Create a unique index

Mysql>create UNIQUE INDEX nameindex on T1 (name);

3. Inserting test data

Mysql>insert into T1 (name) VALUES (' Test ');

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Mysql> select * from T1;

+----+------+

| ID | name |

+----+------+

| 1 | Test |

+----+------+

1 row in Set (0.00 sec)

4. Testing

mysql> replace into T1 (name) VALUES (' Test ');

Query OK, 2 rows Affected (0.00 sec)

Mysql> select * from T1;

+----+------+

| ID | name |

+----+------+

| 2 | Test |

+----+------+

1 row in Set (0.01 sec)

See the effect, when inserting new data, update the old data, if you want to ignore the new data, use ignore

Syntax INSERT IGNORE tablename (column) values (values)

This article is from the "Jeff" blog, so be sure to keep this source http://zhangxz.blog.51cto.com/5490116/1602720

MySQL avoids repeated insert recording methods