尝试在表名上添加别名.这也将使查询更具可读性:

Try putting aliases on table names. It will make the query more readable, too:

SELECT 
    i.`Date`, i.Number, i.Email, i.TID, i.CSW, i.TSW, i.CType, 
    c.Cu, c.Co, c.Ci, c.SID, c.TID, c.SType  
FROM 
    ins.data AS i
  LEFT JOIN 
    Cu.data AS c
      ON i.TID =  c.TID 
ORDER BY 
    i.ID DESC ;