sql語句查詢資料庫,結果集為json資料以供前端、後臺使用
阿新 • • 發佈:2018-12-10
分析:
查詢結果轉換成json需要經過兩個步驟,首先將查詢結果轉成XML資料,然後通過XML資料轉成json。程式碼如下,程式碼部分來源於網路。
一、將查詢結果轉成XML資料
//其中@PSQL 為要查詢的語句,@XML XML格式資料,@XMLString XML轉成字串
DECLARE @PSQL 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 + @PSQL+ ' FOR XML RAW,TYPE,ELEMENTS'
SET @SQL = @SQL + ')'
SET @SQL = @SQL + 'SELECT @XML=[XMLString]FROM[PrepareTable]'
EXEC sp_executesql @SQL, @Paramlist, @ [email protected] OUTPUT
SET @XMLString=CAST(@XML AS VARCHAR(MAX))
SELECT @XML;
SELECT @XMLString;
二、XML資料轉成json
CREATE PROCEDURE [dbo].[SerializeJSON] ( @XML XML, @json_xml NVARCHAR(MAX) OUTPUT ) AS BEGIN DECLARE @XMLString NVARCHAR(MAX); SET @XMLString = CAST(@XML AS NVARCHAR(MAX)); BEGIN TRY--//開始捕捉異常 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--//結束捕捉異常 BEGIN CATCH--//有異常被捕獲 SET @json_xml = @XMLString; END CATCH;--//結束異常處理 END;