参考手册SQL 参考物化视图版本:4.0物化视图 📄️ ALTER MATERIALIZED VIEW功能📄️ CANCEL REFRESH MATERIALIZED VIEW功能📄️ CREATE MATERIALIZED VIEW功能📄️ DROP MATERIALIZED VIEW功能📄️ REFRESH MATERIALIZED VIEW功能📄️ SHOW ALTER MATERIALIZED VIEW功能📄️ SHOW CREATE MATERIALIZED VIEW功能📄️ SHOW MATERIALIZED VIEWS功能