SQL Server Convert integer to binary string

I was wondering if there was an easy way in SQL to convert an integer to its binary representation and then store it as a varchar.

For example 5 would be converted to "101" and stored as a varchar.

Solution 1:

Actually this is REALLY SIMPLE using plain old SQL. Just use bitwise ANDs. I was a bit amazed that there wasn't a simple solution posted online (that didn't invovled UDFs). In my case I really wanted to check if bits were on or off (the data is coming from dotnet eNums).

Accordingly here is an example that will give you seperately and together - bit values and binary string (the big union is just a hacky way of producing numbers that will work accross DBs:

    select t.Number
    , cast(t.Number & 64 as bit) as bit7
    , cast(t.Number & 32 as bit) as bit6
    , cast(t.Number & 16 as bit) as bit5
    , cast(t.Number & 8 as bit) as bit4
    , cast(t.Number & 4 as bit) as bit3
    , cast(t.Number & 2 as bit)  as bit2
    ,cast(t.Number & 1 as bit) as bit1

    , cast(cast(t.Number & 64 as bit) as CHAR(1)) 
    +cast( cast(t.Number & 32 as bit) as CHAR(1))
    +cast( cast(t.Number & 16 as bit)  as CHAR(1))
    +cast( cast(t.Number & 8 as bit)  as CHAR(1))
    +cast( cast(t.Number & 4 as bit)  as CHAR(1))
    +cast( cast(t.Number & 2 as bit)   as CHAR(1))
    +cast(cast(t.Number & 1 as bit)  as CHAR(1)) as binary_string
    --to explicitly answer the question, on MSSQL without using REGEXP (which would make it simple)
    ,SUBSTRING(cast(cast(t.Number & 64 as bit) as CHAR(1)) 
                    +cast( cast(t.Number & 32 as bit) as CHAR(1))
                    +cast( cast(t.Number & 16 as bit)  as CHAR(1))
                    +cast( cast(t.Number & 8 as bit)  as CHAR(1))
                    +cast( cast(t.Number & 4 as bit)  as CHAR(1))
                    +cast( cast(t.Number & 2 as bit)   as CHAR(1))
                    +cast(cast(t.Number & 1 as bit)  as CHAR(1))
                    ,
                    PATINDEX('%1%', cast(cast(t.Number & 64 as bit) as CHAR(1)) 
                                        +cast( cast(t.Number & 32 as bit) as CHAR(1))
                                        +cast( cast(t.Number & 16 as bit)  as CHAR(1))
                                        +cast( cast(t.Number & 8 as bit)  as CHAR(1))
                                        +cast( cast(t.Number & 4 as bit)  as CHAR(1))
                                        +cast( cast(t.Number & 2 as bit)   as CHAR(1))
                                        +cast(cast(t.Number & 1 as bit)  as CHAR(1)  )
                    )
,99)


from (select 1 as Number union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 
    union all select 7 union all select 8 union all select 9 union all select 10) as t

Produces this result:

num  bit7 bit6 bit5 bit4 bit3 bit2 bit1 binary_string   binary_string_trimmed 
1    0    0    0    0    0    0    1    0000001         1
2    0    0    0    0    0    1    0    0000010         10
3    0    0    0    0    0    1    1    0000011         11
4    0    0    0    1    0    0    0    0000100         100
5    0    0    0    0    1    0    1    0000101         101
6    0    0    0    0    1    1    0    0000110         110
7    0    0    0    0    1    1    1    0000111         111
8    0    0    0    1    0    0    0    0001000         1000
9    0    0    0    1    0    0    1    0001001         1001
10   0    0    0    1    0    1    0    0001010         1010

Solution 2:

Following could be coded into a function. You would need to trim off leading zeros to meet requirements of your question.

declare @intvalue int
set @intvalue=5

declare @vsresult varchar(64)
declare @inti int
select @inti = 64, @vsresult = ''
while @inti>0
  begin
    select @vsresult=convert(char(1), @intvalue % 2)+@vsresult
    select @intvalue = convert(int, (@intvalue / 2)), @inti=@inti-1
  end
select @vsresult

Solution 3:

this is a generic base converter

http://dpatrickcaldwell.blogspot.com/2009/05/converting-decimal-to-hexadecimal-with.html

you can do

select reverse(dbo.ConvertToBase(5, 2))   -- 101

Solution 4:

Here's a bit of a change to the accepted answer from Sean, since I found it limiting to only allow a hardcoded number of digits in the output. In my daily use, I find it more useful to either get only up to the highest 1 digit, or specify how many digits I'm expecting back. It will automatically pad the side with 0s, so that it lines up to 8, 16, or whatever number of bits you want.

Create function f_DecimalToBinaryString
    (
        @Dec int,
        @MaxLength int = null
    )
Returns varchar(max)
as Begin

    Declare @BinStr varchar(max) = '';

    -- Perform the translation from Dec to Bin
    While @Dec > 0 Begin

        Set @BinStr = Convert(char(1), @Dec % 2) + @BinStr;
        Set @Dec = Convert(int, @Dec /2);

    End;

    -- Either pad or trim the output to match the number of digits specified.
    If (@MaxLength is not null) Begin
        If @MaxLength <= Len(@BinStr) Begin -- Trim down
            Set @BinStr = SubString(@BinStr, Len(@BinStr) - (@MaxLength - 1), @MaxLength);
        End Else Begin -- Pad up
            Set @BinStr = Replicate('0', @MaxLength - Len(@BinStr)) + @BinStr;
        End;
    End;

    Return @BinStr;

End;