Update a field with the sum value from another table
UPDATE a field from a different table
This snippet retrieves the value from table2.field2, and places it in table1.field1.
update table1 set table1.field1 = table2.field2 from table1,table2 where table1.key = table2.key
UPDATE a field with a SUM from a different table
This snippet adds up multiple entry’s in the second table which have the correct key, and places the sum in the first table. This technique is usefull for totaling seperate lines in table2 into a different table.
update table1 set field1 = ( select sum(table2.field2) from table2 where table1.key = table2.key)