MySQL 沒有就Insert,有就Update 。INSERT ... ON DUPLICATE KEY UPDATE Syntax

摘要:MySQL 沒有就Insert,有就Update 。INSERT ... ON DUPLICATE KEY UPDATE Syntax

http://dev.mysql.com/doc/refman/5.0/en/insert-on-duplicate.html

 

 

INSERT INTO table (a,b,c) VALUES (1,2,3)
  ON DUPLICATE KEY UPDATE c=c+1;

 

If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUEindex or PRIMARY KEY, an UPDATE of the old row is performed. For example, if column a is declared as UNIQUEand contains the value 1, the following two statements have identical effect:

 

只能用在Privary key 或UNIQUE