Generating JSON from TSQL Query

原文地址: http://www.firozansari.com/2008/11/21/generating-json-from-tsql-query/
其他参考: http://www.simple-talk.com/sql/t-sql-programming/consuming-json-strings-in-sql-server/

CREATE PROCEDURE [dbo].[GetJSON] (
@ParameterSQL AS VARCHAR(MAX)
)
AS
BEGIN
 
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))
 
DECLARE @JSON VARCHAR(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)
		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+'",'
 
		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 + ']'
SELECT @JSON
 
END

---->

EXEC GetJSON 'SELECT * FROM dbo.Employee_TBL'

[{"UserId":"7C92EB27-DD81-498E-82CE-18192C940328","FirstName":"Bill","LastName":"Gates","Age":"45","LastLogin":"2008-11-02T00:00:00"},{"UserId":"58E75687-8D0F-423A-8A76-4B1D750F62FD","FirstName":"Steve","LastName":"Job","Age":"52","LastLogin":"2008-10-17T00:00:00"}]