运行下面的查询您将得到一个查询，该查询将从所有表中提供唯一的visitorid。

SELECT 
    CONCAT('SELECT DISTINCT visitorId FROM (',
            REPLACE(query_string, ',', ' UNION '),
            ') union_table') AS final_query
FROM
    (SELECT 
        CONCAT(GROUP_CONCAT('SELECT visitorId FROM ', table_name)) AS query_string
    FROM
        information_schema.tables
    WHERE
        table_name LIKE 'record_%') table_a;

下面的查询将从所有表中获取唯一的visitorid。

SELECT DISTINCT
    visitorId
FROM
    (
    SELECT visitorId FROM record_20181201 
        UNION 
    SELECT visitorId FROM record_20181202 
        UNION 
    SELECT visitorId FROM record_20181203
    ) union_table

SELECT DISTINCT VisitorID FROM DBName.Table1
 UNION 
SELECT DISTINCT VisitorID FROM DBName.Table2 
 UNION 
SELECT DISTINCT VisitorID FROM DBName.Table3

试试这个！！！！！！希望这有帮助。。

您可以从信息架构生成一个带有union的查询字符串。
然后运行该查询，或将其放入视图中。
一 UNION 将返回联合查询的唯一组合结果。
当 UNION ALL 把结果粘在一起。

SELECT GROUP_CONCAT(Qry ORDER BY TblSchema, TblName SEPARATOR ' UNION ')
FROM
(
  SELECT 
   TABLE_SCHEMA as TblSchema,
   TABLE_NAME as TblName,
   CONCAT('select visitorId from ',TABLE_SCHEMA,'.',TABLE_NAME,'\r\n') as Qry
  FROM INFORMATION_SCHEMA.COLUMNS
  WHERE TABLE_NAME LIKE 'record_201812%' 
    AND COLUMN_NAME = 'visitorId'
) Q;