FOR XML PATH 可以将查询结果根据行输出成XML格式

SELECT CAST(OrderID AS varchar)+',' as OrderNo
                                            FROM Product    

CAST函数用于将某种数据类型的表达式显式转换为另一种数据类型

SELECT CAST(OrderID AS varchar)+',' 
                                            FROM Product
                                            
                                            FOR XML PATH('')

转成标准xml

SELECT CAST(OrderID )  as 'MyOrder'
                                            FROM Product
                                            
                                            FOR XML PATH('Order')