SQL入門:テーブル操作
テーブルのコピー
CREATE TABLE meats_tmp SELECT * FROM meats;
NULL値を平均値に置き換える
SELECT *, COALESCE( price, (SELECT SUM(price)/COUNT(*) FROM meats_tmp) ) AS price FROM meats_tmp;
price=0ならNULLを返す
SELECT NULLIF(price, 0) FROM meats_tmp;
行の最小値
SELECT LEAST(col1, col2, col3);
行の最大値
SELECT GREATEST(col1, col2, col3);
整数へ型変換
SELECT *, COALESCE( price, CAST( (SELECT SUM(price)/COUNT(*) FROM meats_tmp) AS UNSIGNED ) ) AS price FROM meats_tmp;