管理指南系统表information_schematable_constraints本页总览table_constraints概述此表仅用于兼容 MySQL 行为。永远为空。所属数据库information_schema表信息列名类型说明CONSTRAINT_CATALOGvarchar(512)CONSTRAINT_SCHEMAvarchar(64)CONSTRAINT_NAMEvarchar(64)TABLE_SCHEMAvarchar(64)TABLE_NAMEvarchar(64)CONSTRAINT_TYPEvarchar(64)