On Thu, 27 Apr 2000, Dennis Gearon wrote:
> Let me see if I have this correct:
>
> 1/ BLOB and TEXT fields store individual bytes(not multibyte chars);
For MySQL I believe this is the case.
> 2/ ALL 256 possible byte values are allowed.;
Yes.
> 3/ When feeding an insert command (or other commands/functions
> WRITING) to a BLOB field the following values must be preceded
> with the binary value for '\';
> Decimal Display
> a> 000 ''
> b> 034 '"'
> c> 039 '''
> d> 092 '\'
Yes, but quoting functions will do all this for you.
> 4/ What actually gets inserted into the BLOB is only the original byte,
> example:
> A/ MySQL insert(modify, whatever) command receives the following
>
> 3 byte string "3\\" What actually goes into the BLOB is
> "3\".
>
> 5/ NOW, when any MySQL queries, selects, whatever READ that string in
> the BLOB,
> the first byte/char is binary/ascii for '3', the second
> byte/char is binary/ascii for '\'.
> This is also true for any MyOBDC queries or ---ANY---
> transmission of the BLOB
> data from the record to the MySQL commands/functions and any
> DBI's or other
> ways to access the data in the BLOB.
Correct.
> 6/ As long as the function reading the BLOB field is not a string
> function, the 00 bytes
> have no significance.
The 00 have no significance other than what the host language assigns to
it (like strings in C)
> How does one index into the BLOB to read one byte and lets say, test a
> bit in that byte?
Substring function can be used in MySQL.
BTW, just in case: Midgard blobserving does not use MySQL blobs.
Emile
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