Question

Consider this statement:

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

I need the value of d.

Is it possible to obtain it without performing a further SELECT?

There is a unique index on a,b,c. Would this index be used for better performance? This table will have a large number of rows.

Answer 1

Assuming you will be running both queries using the same connection, You can use the LAST_INSERT_ID(expr) function to set the current value of d, and check the value of LAST_INSERT_ID() together with the ROW_COUNT() function to find out if the record was inserted or updated:

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

SELECT IF(ROW_COUNT() = 2, LAST_INSERT_ID(), 0 /*default value*/) ;

You can also use session variables:

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

SELECT IF(ROW_COUNT() = 2, @tmp, 0 /*default value*/) ;