Table: sisavath_keobounphanh
Columns: name
took_office
left_office
president
party

Question: What is Left Office, when Took Office is 2006?
SQL: SELECT "left_office" FROM sisavath_keobounphanh WHERE "took_office" = '2006'

Question: What is Left Office, when Party is Vacant (1999-2001)?
SQL: SELECT "left_office" FROM sisavath_keobounphanh WHERE "party" = 'vacant (1999-2001)'

Question: What is Name, when President is Khamtai Siphandon, and when Left Office is 1999?
SQL: SELECT "name" FROM sisavath_keobounphanh WHERE "president" = 'khamtai siphandon' AND "left_office" = '1999'

Question: What is Party, when Name is Oudom Khattigna?
SQL: SELECT "party" FROM sisavath_keobounphanh WHERE "name" = 'oudom khattigna'

Question: What is Party, when Took Office is 1998?
SQL: SELECT "party" FROM sisavath_keobounphanh WHERE "took_office" = '1998'

Question: What is Left Office, when Took Office is 1998?
SQL: SELECT "left_office" FROM sisavath_keobounphanh WHERE "took_office" = '1998'