如果满足两列（无论顺序）的条件，则INSERT或UPDATE

Question

I want to do the following:

INSERT INTO table1 (term1, term2, number) values ('A','B',10); 

however if values A and B are already present in table1 regardless of their order, ie. the predicate

(term1='A' && term2='B') OR (`term1='B' && term2='A')

holds true, then I just want to update column number. Is there any way of doing that?

Answer 1

A (perhaps the ) clean way to handle this situation is to use INSERT ... ON DUPLICATE KEY UPDATE , read the documentation .

If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, MySQL performs an UPDATE of the old row

The important part is would cause a duplicate value in a UNIQUE index . Therefore you need to create an multicolumn unique index .

Now I'm not sure if you can manage the order that way, therefore I'd create an extra field with the concatenation of the sorted values of your fields, and have that field uniquely indexed.

EDIT : Instead of storing the concatenation your fields, you could also just store the hash and index it.

Answer 2

Thanks @okiharaherbst,

This is what I did: I added new column "uniqueKey" as primary key and insert goes as follows:

INSERT INTO table1(term1,term2,num,uniquekey) VALUES ( "a","b",10, 
concat(greatest(term1,term2),least(term1,term2))) on duplicate key update num=10;