SQL is...

[データ表示]

SELECT st.code, st.company, mk.market, bz.biz FROM t_stox AS st LEFT JOIN t_market AS mk ON st.market_id = mk.id LEFT JOIN t_biz AS bz ON st.biz_id = bz.id WHERE bz.biz = '鉱業' ;

[件数取得]

SELECT count(code) FROM t_stox AS st LEFT JOIN t_market AS mk ON st.market_id = mk.id LEFT JOIN t_biz AS bz ON st.biz_id = bz.id WHERE bz.biz = '鉱業' ;