如何在特定单词后截断字符串？

Question

我有一个数据类型为nvarchar(max)的字符串，如下所示：

declare @cbCheckdate nvarchar(max) ='
{"request_id":"364202","final_decision":"FAIL","derived_Attribute_1":"PASS|Number of active MFI :1",
"derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
"derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
"derived_Attribute_2":"FAIL|Overdue Amount:17984.0","derived_Attribute_5":"PASS|Write off amount:0.0",
"cbResponseMsg":"Final Decision:FAIL || Number of active MFI :1 || Total Exposure + Applied Amount :53051.0 
|| Number of Total Active Institutions :2 || FAILOve'

我需要像下面这样截断上面的字符串：

declare @cbCheckdate nvarchar(max) ='{"request_id":"364202","final_decision":"FAIL","derived_Attribute_1":"PASS|Number of active MFI :1",
"derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
"derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
"derived_Attribute_2":"FAIL|Overdue Amount:17984.0","derived_Attribute_5":"PASS|Write off amount:0.0"'

基本上，我需要做的是：如果我的字符串中包含此单词cbResponseMsg，那么我需要删除此单词及其后的所有文本。

Answer 1

此输入可能是JSON格式，因此，如果您使用SQL Server 2016+，则可以使用JSON_MODIFY()函数从输入JSON中删除cbResponseMsg键：

声明：

DECLARE @cbCheckdate nvarchar(max) = '{
   "request_id":"364202",
   "final_decision":"FAIL",
   "derived_Attribute_1":"PASS|Number of active MFI :1",
   "derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
   "derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
   "derived_Attribute_2":"FAIL|Overdue Amount:17984.0",
   "derived_Attribute_5":"PASS|Write off amount:0.0",
   "cbResponseMsg":"Final Decision:FAIL || Number of active MFI :1 || Total Exposure + Applied Amount :53051.0 || Number of Total Active Institutions :2 || FAILOve"
}'

SELECT @cbCheckdate = JSON_MODIFY(@cbCheckdate, '$.cbResponseMsg', NULL)
SELECT @cbCheckdate

结果：

{
   "request_id":"364202",
   "final_decision":"FAIL",
   "derived_Attribute_1":"PASS|Number of active MFI :1",
   "derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
   "derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
   "derived_Attribute_2":"FAIL|Overdue Amount:17984.0",
   "derived_Attribute_5":"PASS|Write off amount:0.0"
}

Answer 2

您可以这样做

set @cbCheckdate = left(@cbCheckdate, CHARINDEX('cbResponseMsg', @cbCheckdate) -2)  select @cbCheckdate

Answer 3

由于您使用的是SQL Server 2014，并且还没有内置的JSON支持，因此我可能会为此编写一个小函数：

CREATE OR ALTER FUNCTION dbo.TruncateAfter(@Input NVARCHAR(MAX), @Delimiter NVARCHAR(100))
RETURNS NVARCHAR(MAX)
AS
BEGIN
    DECLARE @Result NVARCHAR(MAX);

    DECLARE @DelimiterPos INT;
    SET  @DelimiterPos = CHARINDEX(@Delimiter, @Input);

    IF (@DelimiterPos > 0)
        SET @Result = TRIM(LEFT(@Input, @DelimiterPos - 1));
    ELSE
        SET @Result = @Input;

    RETURN @Result;
END

现在，您可以使用两个参数调用此函数-输入和要查找的“定界符”。如果找到定界符，则从其位置开始的所有文本都会被截断-如果定界符未出现在输入中，则返回整个输入：

DECLARE @cbCheckdate NVARCHAR(MAX) = N'
{"request_id":"364202","final_decision":"FAIL","derived_Attribute_1":"PASS|Number of active MFI :1",
"derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
"derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
"derived_Attribute_2":"FAIL|Overdue Amount:17984.0","derived_Attribute_5":"PASS|Write off amount:0.0",
"cbResponseMsg":"Final Decision:FAIL || Number of active MFI :1 || Total Exposure + Applied Amount :53051.0 
|| Number of Total Active Institutions :2 || FAILOve'

DECLARE @Delimiter NVARCHAR(MAX) = N'cbResponseMsg';

SELECT 
    dbo.TruncateAfter (@cbCheckdate, @Delimiter)

应返回所需的输出。

Answer 4

这是使用内置函数stuff，charindex，reverse，len和sign的无用户定义功能的安全方法：

declare @cbCheckdate nvarchar(max) ='
{"request_id":"364202","final_decision":"FAIL","derived_Attribute_1":"PASS|Number of active MFI :1",
"derived_Attribute_4":"PASS|Total Exposure + Applied Amount :53051.0",
"derived_Attribute_3":"PASS|Number of Total Active Institutions :2",
"derived_Attribute_2":"FAIL|Overdue Amount:17984.0","derived_Attribute_5":"PASS|Write off amount:0.0",
"cbResponseMsg":"Final Decision:FAIL || Number of active MFI :1 || Total Exposure + Applied Amount :53051.0 
|| Number of Total Active Institutions :2 || FAILOve';

declare @delimiter nvarchar(100) = '"cbResponseMsg"';

SELECT  REVERSE(
            STUFF(
                REVERSE(@cbCheckdate), 
                1,
                CHARINDEX(REVERSE(@delimiter), REVERSE(@cbCheckdate)) + 
                    LEN(@delimiter) * SIGN(CHARINDEX(@delimiter, @cbCheckdate)),
            '')
        )

这里是从内到外的细分：

• 如果找不到分隔符，则返回0；如果在字符串中找到，则返回正整数。
• [CHARINDEX(@delimiter, @cbCheckdate)将为SIGN返回0，为正数返回0，或（与这种情况无关）为负数返回1。
• [-1将返回

  CHARINDEX(REVERSE(@delimiter), REVERSE(@cbCheckdate)) + 
   LEN(@delimiter) * SIGN(CHARINDEX(@delimiter, @cbCheckdate))

  ，如果找不到分隔符，或者是表示分隔符开始到字符串结尾之间的字符数的正整数。
• 0函数将一个空字符串放入源字符串中，从第一个字符（STUFF）开始，并替换作为第三个参数的字符数。
• 最后，由于这都是在反向字符串上完成的，因此再返回1结果一次以正确的顺序返回字符串。