Use the following script -

DECLARE @StringVARCHAR(255),

@SearchStrVARCHAR(255)

SET @String='The quick brown fox jumps over the lazy dog'

SET @SearchStr='fox '+'////'

SELECT SUBSTRING(@String,CHARINDEX(LEFT(@SearchStr,LEN(@SearchStr)-4),@String),LEN(@SearchStr)-4)

Note: You can directly have the column name in place of the variable.