user: Question: What is the total round when db was the position, and the pick less than 21, and jeff welch as the name?
Columns: ['Round', 'Pick', 'Overall', 'Name', 'Position', 'College']
Types: ['real', 'real', 'real', 'text', 'text', 'text']
Sample row: [8.0, 21.0, 203.0, 'Moses Denson', 'RB', 'Maryland Eastern Shore [o ]']
SQL:

assistant: SELECT SUM("Round") FROM "Table" WHERE "Position" = 'db' AND "Name" = 'jeff welch' AND "Pick" < 21.0;