How to store array in one column in Sqlite3?

Question

Is there any way to store an array of integers in one column of table? I want o/p like this:

ident | value                                                            


        

Answer 1

SQLite3 does not support arrays directly. See here the type it supports. Basically, it only does Ints, Floats and Text.

To accomplish what you need, you have to use a custom encoding, or use an FK, i.e. create another table, where each item in the array is stored as a row.

Answer 2

This is one way of serializing and deserializing data:

#include <string>
#include <vector>
#include <sstream>
#include <iostream>

std::vector<std::string> deserialize_array(std::string const &csv)
{
  std::istringstream parse(csv);
  std::vector<std::string> ret;
  for(std::string token; std::getline(parse, token, ','); ret.push_back(token));
  return ret;
}

std::string serialize_array(std::string* array_ptr, std::size_t N)
{
  std::ostringstream cat;
  for(std::size_t index= 0; index< N; ++ index)
    cat<< array_ptr[index]<< ',';
  std::string ret= cat.str();
  return ret.substr(0, ret.size()-1);
}

int main()
{
  std::string data= "1,2,3";
  std::cout<< "Data: "<< data<< std::endl;
  std::vector<std::string> deserialized= deserialize_array(data);
  std::string serialized= serialize_array(deserialized.data(), deserialized.size());
  std::cout<< "Serialized + Deserialized: "<< serialized<< std::endl;
}

Instead of spending time parsing parentheses and extra commas, you can serialize as csv and read two by two when processing the deserialized data.

Answer 3

Sorry to Necro, just came across the problem myself and found a solution.

As stated already SQLite has no support for arrays, so you can't store them as such. Try this, I had the same problem;

Instead of storing array elements individually, you can store them as a large string and use a string function or Regular expression to parse them back into their types. An C# example

int[] myArray = new int[] {8,4,345,378,34456,7};

string Arraystring = myArray[0].ToString();

for(int i = 1; i < myArray.Length; i++) { 
Arraystring += "," + myArray[i].ToString();

}

This will turn the array into a single string, now we take the string and insert it into the table as a string, when you read the string use this code to get the array back. Another C# example

string value; //assign this via Reader
string[] tokens = values.Split(',');

int[] myItems = Array.ConvertAll<string, int>(tokens, int.Parse);

this will only work with single dimensional arrays, multi-dimensional can get tricky when it comes to parsing the strings.

Answer 4

This is what I envision, though it may be incorrect:

<table>
  <citation>
    <citation ID>
    <citation content>
    <citation publication date>

CREATE TABLE citation
(
    citation_ID INTEGER PRIMARY KEY AUTOINCREMENT,
    citation VARCHAR(255)
    published datetime
    )


<table>
  <source doc>
    <source doc ID>
    <source doc content>

CREATE TABLE source
(
    source_ID INTEGER PRIMARY KEY AUTOINCREMENT,
    source VARCHAR(5000)
    )

<citation_to_source table> //table in question
  <relationship>
    <relationship ID>
    <citation ID>
    <source doc ID>

CREATE TABLE citation_to_source //table in question
(
    relationship_id INTEGER,
    citation_ID INTEGER,
            source_ID INTEGER,
            FOREIGN KEY(citation_ID) REFERENCES citation(citation_ID)
            FOREIGN KEY(source_ID) REFERENCES source(source_ID)
    )

Output format:

<content>
  <relationship ID>
  <unique source document content>
  <enumerate citation IDs>