DECLARE @stringDatetime CHAR(14) = '20160823160000' -- yyyyMMddhhmmss
DECLARE @convertedDatetime DATETIME = NULL
SELECT @convertedDatetime = CAST((SUBSTRING(@stringDatetime,1,4) + '-' +
SUBSTRING(@stringDatetime,5,2) + '-' +
SUBSTRING(@stringDatetime,7,2) + ' ' +
SUBSTRING(@stringDatetime,9,2) + ':' +
SUBSTRING(@stringDatetime,11,2) + ':' +
SUBSTRING(@stringDatetime,13,2)) AS DATETIME)
SELECT @convertedDatetime AS convertedDatetime
참고 : [MSSQL] SUBSTRING 문자열 자르기
demo : http://rextester.com/TWLEM83934