BigQuery UPDATE from another table
Update rows using data from another table
UPDATE from table example
UPDATE myDataset.Inventory T\nSET quantity = n.quantity\nFROM (\nselect quantity, product from myDataset.NewArrivals\n)n\nWHERE i.product = n.product
Syntax reference
UPDATE target_name [[AS] alias]\nSET set_clause\n[FROM from_clause]\nWHERE condition\n\nset_clause ::= update_item[, ...]\n\nupdate_item ::= column_name = expression