Table: arch_bridge_spans
Columns: rank
name
span_metres
span_feet
material
year_opened
location
country

Question: What is the sum of Year opened when steel was the material with a Span feet of 1476?
SQL: SELECT SUM("year_opened") FROM arch_bridge_spans WHERE "material" = 'steel' AND "span_feet" = 1476

Question: What is the sum of Year opened when the span feet is more than 1247, and the spam metres is 384?
SQL: SELECT SUM("year_opened") FROM arch_bridge_spans WHERE "span_feet" > 1247 AND "span_metres" = 384