What is the "season joined league" for the club that had 15 seasons at this level?
CREATE TABLE table_name_54 (season_joined_league VARCHAR, seasons_at_this_level VARCHAR)
SELECT season_joined_league FROM table_name_54 WHERE seasons_at_this_level = "15 seasons"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_name_54 (season_joined_league VARCHAR, seasons_at_this_level VARCHAR) Question: What is the "season joined league" for the club that had 15 seasons at this level? [/INST] SELECT season_joined_league FROM table_name_54 WHERE seasons_at_this_level = "15 seasons" </s>