MSSQL Replace

update [TableNAME] set [ColumnName] = REPLACE([ColumnName]
      ,'G:\eBooks\'
      ,'D:\Elib_WEB\eBooks\')
  FROM [DbNAME].[dbo].[TableNAME]
  where [ColumnName] like 'G:\eBooks\%'


-----------Update
  update[TableNAME] SET [ColumnName] = 'PUB'
  FROM [DbNAME].[dbo].[TableNAME]
  where [ColumnName] is not NULL  and [ColumnName2] is NULL        
     





REF----------------------------------
https://juell.tian.yam.com/posts/22958926