CREATE TABLE table_1966992_1 (census_2006_population INT, lga_name VARCHAR)

What is the maximum 2006 census population of LGA name Opobo/Nkoro?
SELECT MAX(census_2006_population) FROM table_1966992_1 WHERE lga_name = "Opobo/Nkoro"
SELECT MAX("census_2006_population") FROM "table_1966992_1" WHERE "Opobo/Nkoro" = "lga_name"