很久之前用到的，现在整理在这，里面一些代码来源于网上，不过有些bug已被我修改了。

1.查询结果转XML

DECLARE @ParameterSQL NVARCHAR(MAX)='SELECT * FROM table';
DECLARE @SQL NVARCHAR(MAX)
DECLARE @XMLString VARCHAR(MAX)
DECLARE @XML XML
DECLARE @Paramlist NVARCHAR(1000)
SET @Paramlist = N'@XML XML OUTPUT'
SET @SQL = 'WITH PrepareTable (XMLString)'
SET @SQL = @SQL + 'AS( '
SET @SQL = @SQL + @ParameterSQL+ ' FOR XML RAW,TYPE,ELEMENTS'
SET @SQL = @SQL + ')'
SET @SQL = @SQL + 'SELECT @XML=[XMLString]FROM[PrepareTable]'
EXEC sp_executesql @SQL, @Paramlist, @XML=@XML OUTPUT
SET @XMLString=CAST(@XML AS VARCHAR(MAX))
SELECT @XML;
SELECT @XMLString;

其中 @ParameterSQL 为要查询的语句， @XML XML格式数据， @XMLString XML转成字符串

2.查询结果转JSON

查询结果转换成json需要经过两个步骤，首先将查询结果转成XML数据，然后通过XML数据转成json
XML转JSON的存储过程如下：

CREATE PROCEDURE [dbo].[SerializeJSON] (
     @XML  XML,
     @json_xml  NVARCHAR(MAX) OUTPUT
BEGIN
    DECLARE @XMLString NVARCHAR(MAX);
    SET @XMLString = CAST(@XML AS NVARCHAR(MAX));
    BEGIN TRY--//开始捕捉异常
        DECLARE @JSON NVARCHAR(MAX);
        DECLARE @Row VARCHAR(MAX);
        DECLARE @RowStart INT;
        DECLARE @RowEnd INT;
        DECLARE @FieldStart INT;
        DECLARE @FieldEnd INT;
        DECLARE @KEY VARCHAR(MAX);
        DECLARE @Value VARCHAR(MAX);
        DECLARE @StartRoot VARCHAR(100);
        SET @StartRoot = '<row>';
        DECLARE @EndRoot VARCHAR(100);
        SET @EndRoot = '</row>';
        DECLARE @StartField VARCHAR(100);
        SET @StartField = '<';
        DECLARE @EndField VARCHAR(100);
        SET @EndField = '>';
        SET @RowStart = CHARINDEX(@StartRoot, @XMLString, 0);
        SET @JSON = '';
        WHILE @RowStart>0
        BEGIN
            SET @RowStart = @RowStart + LEN(@StartRoot);
            SET @RowEnd = CHARINDEX(@EndRoot, @XMLString, @RowStart);
            SET @Row = SUBSTRING(@XMLString, @RowStart, @RowEnd - @RowStart);
            SET @JSON = @JSON + '{';
            --//for each row
            SET @FieldStart = CHARINDEX(@StartField, @Row, 0);
            WHILE @FieldStart>0
            BEGIN
                --//parse node key
                SET @FieldStart = @FieldStart + LEN(@StartField);
                SET @FieldEnd = CHARINDEX(@EndField, @Row, @FieldStart);
                DECLARE @end INT = CHARINDEX('/>', @Row, @FieldStart);
                IF @end<1
                    OR @end>@FieldEnd
                BEGIN
                    SET @KEY = SUBSTRING(@Row, @FieldStart, @FieldEnd - @FieldStart);
                    SET @JSON = @JSON + '"' + @KEY + '":';
                    --//parse node value
                    SET @FieldStart = @FieldEnd + 1;
                    SET @FieldEnd = CHARINDEX('</', @Row, @FieldStart);
                    SET @Value = SUBSTRING(@Row, @FieldStart, @FieldEnd - @FieldStart);
                    SET @JSON = @JSON + '"' + @Value + '",';
                END;
                SET @FieldStart = @FieldStart + LEN(@StartField);
                SET @FieldEnd = CHARINDEX(@EndField, @Row, @FieldStart);
                SET @FieldStart = CHARINDEX(@StartField, @Row, @FieldEnd);
            END;
            IF LEN(@JSON)>0
                SET @JSON = SUBSTRING(@JSON, 0, LEN(@JSON));
            SET @JSON = @JSON + '},';
            --// for each row
            SET @RowStart = CHARINDEX(@StartRoot, @XMLString, @RowEnd);
        END;
        IF LEN(@JSON)>0
            SET @JSON = SUBSTRING(@JSON, 0, LEN(@JSON));
        --//SET @JSON = '[' + @JSON + ']';
        SET @json_xml = @JSON;
    END TRY--//结束捕捉异常
    BEGIN CATCH--//有异常被捕获
        SET @json_xml = @XMLString;
    END CATCH;--//结束异常处理
END;