When you get YAPE::Regex::Explain installed the result for your 'old' regex should be 

The regular expression:

(?-imsx:&[^(amp;)|(lt;)|(gt;)])

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  &                        '&'
----------------------------------------------------------------------
  [^(amp;)|(lt;)|(gt;)     any character except: '(', 'a', 'm', 'p',
  ]                        ';', ')', '|', '(', 'l', 't', ';', ')',
                           '|', '(', 'g', 't', ';', ')'
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

[download]
and for mine 
The regular expression:

(?-imsx:(&(?!(?:amp|lt|gt);)|[><]))

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    &                        '&'
----------------------------------------------------------------------
    (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
      (?:                      group, but do not capture:
----------------------------------------------------------------------
        amp                      'amp'
----------------------------------------------------------------------
       |                        OR
----------------------------------------------------------------------
        lt                       'lt'
----------------------------------------------------------------------
       |                        OR
----------------------------------------------------------------------
        gt                       'gt'
----------------------------------------------------------------------
      )                        end of grouping
----------------------------------------------------------------------
      ;                        ';'
----------------------------------------------------------------------
    )                        end of look-ahead
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    [><]                     any character of: '>', '<'
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

[download]
and your new regex 
The regular expression:

(?-imsx:&(?!(amp;)|(lt;)|(gt;)))

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  &                        '&'
----------------------------------------------------------------------
  (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
    (                        group and capture to \1:
----------------------------------------------------------------------
      amp;                     'amp;'
----------------------------------------------------------------------
    )                        end of \1
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    (                        group and capture to \2:
----------------------------------------------------------------------
      lt;                      'lt;'
----------------------------------------------------------------------
    )                        end of \2
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    (                        group and capture to \3:
----------------------------------------------------------------------
      gt;                      'gt;'
----------------------------------------------------------------------
    )                        end of \3
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

[download]
poj

In reply to Re^7: Interpolating subroutine call in SQL INSERT INTO SELECT statement by poj
in thread Interpolating subroutine call in SQL INSERT INTO SELECT statement by shadowsong

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