如果已存在具有相同值的行，则增加列

This one's a bit too tricky for my SQL-foo.

这对我的SQL-foo来说有点太棘手了。

What I need to do is insert a new row (which contains 3 columns), unless a row already exists where two of those values are the same, and if it does exist, I need to increment the third value on that row.

我需要做的是插入一个新行(包含3列),除非已经存在一行,其中两个值相同,如果它确实存在,我需要增加该行的第三个值。

Imagine the two values being a relationship (a, b) and the third value being the relationships's strength (which increases with every ocurrence of that relationship).

想象一下,两个值是关系(a,b),第三个值是关系的强度(随着该关系的每一次发生而增加)。

Thanks in advance!

提前致谢!

1 个解决方案

#1

INSERT
INTO    a_b (a, b, strength)
VALUES  ($a, $b, 1)
ON DUPLICATE KEY
UPDATE  strength = strength + 1

Make sure you have a UNIQUE (a, b) or PRIMARY KEY (a, b) constraint on the table

确保表上有一个UNIQUE(a,b)或PRIMARY KEY(a,b)约束