Xây dựng hàm chuyển đổi dữ liệu từ font TCVN3 sang Unicode trong Microsoft SQL Server

Xây dựng Scalar Function để chuyển đổi dữ liệu từ font TCVN3 sang Unicode trong Microsoft SQL Server

/****** Object:  UserDefinedFunction [dbo].[TCVN2Unicode]    Script Date: 12/24/2008 01:00:14 ******/
SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER OFF
GO
CREATE FUNCTION [dbo].[TCVN2Unicode] (@strInput VARCHAR(4000))
RETURNS NVARCHAR(4000)
AS
BEGIN
    DECLARE @TCVN CHAR(671)
    DECLARE @UNICODE CHAR(671)
    SET @TCVN = ',184 ,181 ,182 ,183 ,185 ,168 ,190 ,187 ,188 ,189 ,198 ,169 ,202 ,199 ,200 ,201 ,203 ,208 ,204 ,206 ,207 ,209 ,170 ,213 ,210 ,211 ,212 ,214 ,221 ,215 ,216 ,220 ,222 ,227 ,223 ,225 ,226 ,228 ,171 ,232 ,229 ,230 ,231 ,233 ,172 ,237 ,234 ,235 ,236 ,238 ,243 ,239 ,241 ,242 ,244 ,173 ,248 ,245 ,246 ,247 ,249 ,253 ,250 ,251 ,252 ,254 ,174 ,184 ,181 ,182 ,183 ,185 ,161 ,190 ,187 ,188 ,189 ,198 ,162 ,202 ,199 ,200 ,201 ,203 ,208 ,204 ,206 ,207 ,209 ,163 ,213 ,210 ,211 ,212 ,214 ,221 ,215 ,216 ,220 ,222 ,227 ,223 ,225 ,226 ,228 ,164 ,232 ,229 ,230 ,231 ,233 ,165 ,237 ,234 ,235 ,236 ,238 ,243 ,239 ,241 ,242 ,244 ,166 ,248 ,245 ,246 ,247 ,249 ,253 ,250 ,251 ,252 ,254 ,167 ,'
    SET @UNICODE = ',225 ,224 ,7843,227 ,7841,259 ,7855,7857,7859,7861,7863,226 ,7845,7847,7849,7851,7853,233 ,232 ,7867,7869,7865,234 ,7871,7873,7875,7877,7879,237 ,236 ,7881,297 ,7883,243 ,242 ,7887,245 ,7885,244 ,7889,7891,7893,7895,7897,417 ,7899,7901,7903,7905,7907,250 ,249 ,7911,361 ,7909,432 ,7913,7915,7917,7919,7921,253 ,7923,7927,7929,7925,273 ,193 ,192 ,7842,195 ,7840,258 ,7854,7856,7858,7860,7862,194 ,7844,7846,7848,7850,7852,201 ,200 ,7866,7868,7864,202 ,7870,7872,7874,7876,7878,205 ,204 ,7880,296 ,7882,211 ,210 ,7886,213 ,7884,212 ,7888,7890,7892,7894,7896,416 ,7898,7900,7902,7904,7906,218 ,217 ,7910,360 ,7908,431 ,7912,7914,7916,7918,7920,221 ,7922,7926,7928,7924,272 ,'
    IF @strInput IS NULL RETURN NULL
    IF @strInput = '' RETURN NULL
    DECLARE @strOutput NVARCHAR(4000)
    DECLARE @COUNTER INT
    DECLARE @POSITION INT
    SET @COUNTER = 1
    SET @strOutput = ''
    WHILE (@COUNTER <= LEN(@strInput))
    BEGIN
        SET @POSITION = CHARINDEX(','+CONVERT(CHAR(4),ASCII(SUBSTRING(@strInput, @COUNTER, 1)))+',', @TCVN, 1)
        IF @POSITION > 0
            SET @strOutput = @strOutput + NCHAR(CONVERT(INT,SUBSTRING(@UNICODE, @POSITION+1, 4)))
        ELSE
            SET @strOutput = @strOutput + SUBSTRING(@strInput, @COUNTER, 1)
        SET @COUNTER = @COUNTER + 1
    END
    RETURN @strOutput
END