SQL 字符串截取左边指定长度字符串中文、英文

代码

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

ALTER FUNCTION [dbo].[substring2] (@rescontent varchar(100), @nlength int,@thchar varchar(100) ) Returns varchar(255)
AS
BEGIN
declare @rest varchar(255)
if(datalength(@rescontent)>34)
set @rest=(substring(@rescontent,0,17)+''+@thchar)
else
set @rest=@rescontent
return @rest
END

select dbo.FN_MYSUBSTRING(infocontent_title,34) from t_p_infocontent
creater FUNCTION [dbo].[FN_MYSUBSTRING](
@Content nvarchar(4000),
@Size int
@suffix varchar(200)
)
RETURNS nvarchar(4000)
AS
BEGIN
-- SET @Content = N'Office of Commissioner Insurance - Establishment of an Independent Insurance Authority in Hong Kong (2009)'
-- SET @Size = 26
SET @Content = LTRIM(RTRIM(REPLACE( REPLACE(@Content,CHAR(10),' '),CHAR(13),' ')))
if @Size > 0 AND @Size < 2 * LEN (@Content)
begin
declare @Pos INT --Current pointer
DECLARE @sPos INT --Current stay pointer
DECLARE @PrePos INT --Previous stay pointer
declare @tempS nvarchar(4)
DECLARE @tempNextS nvarchar(4)
declare @tempSize INT
DECLARE @unicodeS INT
DECLARE @unicodeNextS INT
set @Pos = 1
set @sPos = 0
SET @prePos = 0
SET @tempS = N''
SET @tempNextS = N''
SET @tempSize = 0

WHILE @Pos < len(@Content)
BEGIN
IF @tempSize < @Size
BEGIN
SET @tempS = SUBSTRING(@Content,@Pos,1)
SET @tempNextS = SUBSTRING(@Content,@Pos+ 1,1)
SET @unicodeS = UNICODE(@tempS)
SET @unicodeNextS = UNICODE(@tempNextS)

IF @unicodeS > 254
BEGIN
SET @tempSize = @tempSize + 2
SET @sPos = @Pos
END
ELSE
BEGIN
SET @tempSize = @tempSize + 1

-- Do not turncate the word just length as @Size by add symbol before and after the word
IF @unicodeS < 48 OR (@unicodeS > 57 AND @unicodeS < 65) OR (@unicodeS > 90 AND @unicodeS < 97) OR @unicodeS > 122
OR @unicodeNextS < 48 OR (@unicodeNextS > 57 AND @unicodeNextS < 65) OR (@unicodeNextS > 90 AND @unicodeNextS < 97) OR @unicodeNextS > 122
BEGIN
SET @sPos = @Pos
END

END
END

IF @tempSize > @Size - 2 AND @unicodeNextS > 254 -- if next letter is Chinese then turncate the string
BEGIN
SET @tempSize = @Size
SET @sPos = @Pos
END
ELSE IF @tempSize = @Size AND @PrePos = @sPos -- else if the English word length is large than the @Size then turncate the word
BEGIN
SET @sPos = @Pos
END

IF @tempSize >= @Size
BEGIN
set @Content = left(@Content, @sPos)+@suffix
-- +'@'
-- + nchar(13)
-- + right(@Content, len(@Content) - @sPos)
SET @tempSize = 0
SET @PrePos = @sPos
set @Pos = @sPos + 1
END
set @Pos = @Pos + 1
SET @unicodeS = 0
SET @unicodeNextS = 0
END

END

RETURN @Content
END