Re: [sqlite] Wish to store a C structure in sqlite column

[AJ]

I hackish method might be something like this:


struct s
{
 ...
};

struct s  myS;

char buf[sizeof(s)*2];   // *2 as base64 encoding will be approx 33% bigger.
base64_encode( &myS, buf, sizeof(s) );

INSERT INTO table ( myTextField ) VALUES ( 'buf' );


then retrieval is the opposite.












Noel Frankinet wrote:

Narendran a écrit :

Noel Frankinet wrote:

Narendran a écrit :

Dear Friends,


  I am in the process of forming a Generic API,(sql oriented and
BerkelyDB

and sister databases). In the process of integration ,i like to store a

Structure in Sqlite.
 as far as my knowledge SQLITE allows me to declare the column types
suppoted by the programming languare or say i am using blob . My
requirement
is i wish to store a structure in the SQLite column.

I am unable to form a sql statement to store the structure ,i am also

not
clear with whether i can have a strucure as column type.

suggestions will be really helpful.

 Thanking you,
 B.Narendran

You will need to turn your c struct into a blob and store that blob.

When retrieving the blob, you need a way to turn it back into your struct.

Its releatively easy if your struct does not contains pointers.

Best wishes

--
Noël Frankinet
Gistek Software SA
http://www.gistek.net

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Dear Frankinet,

  Thanks for ur reply,

I am unable to understand what u have said. I am having a structure and I am converting in to a blob. This means i am supposed to remove the '\0' in between the strucure and put a final '\0' (NULL) character . Blob need only

on e null character to terminate it.

I tried to memcopy the structure elements and store them ,I can store but

i am unable to find a way to retrieve it back.
 typedef  struct ethernetcard1
    {
      char port[10];
      char ipaddress[20];
      char mask[20];
      int bandwidth;
  }

what i tried is
 char *buffer;
  int bufferlen;buffersize;
bufferlen = strlen(port)+strlen(ipaddress)+strlen(mask)+sizeof(int)+1;

memcpy(buffer,user.port,strlen(user.port);
buffersize = strlen(user.port);

memcpy(buffer,user.ipaddress,strlen(user.ipaddress));
buffersize += strlen(user.ipaddress);

and finally i included a NULL character to the buffer to make it as string and i can insert in to a text field in sqlite column . I am unable to figure out a way to retrieve it back if i am storing in this way or a blob type I think blob will be similar to this . expecting ur valuable suggestion.

Thanking you,

Narendran

hello Narendran,

Unfortunately, I'm still using 2.xx, so I encode the blob in character using sqlite_encode and I decode it back when I get it from sqlite. You are on the right track, but for string you should have a way to store the length. I have written some encoding function (like write_string and read_string) to help encoding and decoding from the buffer (and avoi all those mesy memcpy).

I hope this help
Best wishes

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