php and mysql (for numerical operations)

Question

i have two tables in mysql . i want to add or subtract values from one table from another. i expect clear answer. please help me

Answer 1

You can use UDPDATE JOIN.

Example:

IF there is a PK->FK relationship:

UPDATE table1 t1 inner join table2 t2 on t1.id = t2.id set t1.col1 = t1.col1+t2.coln;

other wise:

UPDATE table1 t1 cross join table2 t2 set t1.col1 = t1.col1+t2.coln where some condition;

Hope this will help you.