select case column_name1 

    when value1 then result1 

    [when value2 then result2.....][else result] 

    end [as column_new_name]

    [,case 

     when expr1 then result1 

    [when expr2 then result2...]

    [else result] 

    end [as column_new_name]

    [,case...]

    ]

from tb_name;