Sqlite : format an integer - sqlite

Question

Is it possible to format an integer column to have a comma as a thousandth digit separator in Sqlite? I would like the query result to be as follows.
Id Name Price
1 Product1 1,000
2 Product2 2,500

Answer 1

There is not an internal number formatting function built into SQLite, but you can create a user-defined function to create one.
Here's a working example. Uses integers and will need adjustment for floats.
#import <sqlite3.h>
static char *sepnum(int num, char *buf, size_t buflen, char sepch)
{
int len = 0, negative = 0;
if (!buf || buflen == 0) return buf;
if (num < 0)
{
negative = 1;
num = abs(num);
}
for (int i=1;;i++)
{
if (buflen>len+1) buf[len++] = '0' + (num % 10);
num /= 10;
if (num==0) break;
if ((i % 3) == 0 && buflen>len+1) buf[len++] = sepch;
}
if (negative && buflen>len+1) buf[len++] = '-';
for (int i=0;i<len/2;i++)
{
buf[len] = buf[i];
buf[i] = buf[len-i-1];
buf[len-i-1] = buf[len];
}
if (buflen>len) buf[len] = '\0';
else buf[0] = '\0';
return buf;
}
static void nformat(sqlite3_context *context, int argc, sqlite3_value **argv)
{
if (argc == 1)
{
int num = sqlite3_value_int(argv[0]);
char buf[500] = "";
if (sepnum(num, buf, sizeof(buf), ','))
{
sqlite3_result_text(context, buf, -1, SQLITE_TRANSIENT);
return;
}
}
sqlite3_result_null(context);
}
int main(int argc, char *argv[])
{
sqlite3 *db;
sqlite3_open(":memory:", &db);
sqlite3_stmt *stmt;
sqlite3_create_function(db, "nformat", 1, SQLITE_UTF8, NULL, &nformat, NULL, NULL);
sqlite3_prepare(db, "select nformat(1234)", -1, &stmt, NULL);
sqlite3_step(stmt);
printf("[%s]\n", sqlite3_column_text(stmt, 0));
}

Answer 2

If your data is stored in a table and you are using SQLite version 3.8.3 or higher, then it is possible to accomplish what you want using a recursive CTE.
Below is a working SQL example of what I'm referring to.
WITH
NBR_LIST_ETL AS
(
SELECT
A.*,
CAST(REPLACE(NBR_LENGTH % 3, 0, 3) AS INTEGER)
AS SUB_STRING_LENGTH
FROM
(
SELECT
ID, -- INTEGER PRIMARY KEY COLUMN
NBR, -- INTEGER COLUMN YOU WANT TO FORMAT W/ COMMAS
LENGTH(NBR)
AS NBR_LENGTH
FROM
NBR_LIST A -- REPLACE NBR_LIST W/ YOUR TABLE NAME
) A
),
NBR_FORMAT_RECURSIVE AS
(
SELECT
ID,
SUBSTR(NBR, 1, SUB_STRING_LENGTH)
AS NBR_SEGMENT,
SUBSTR(NBR, SUB_STRING_LENGTH + 1)
AS NBR_REMAINING,
NBR_LENGTH - SUB_STRING_LENGTH
AS NBR_LENGTH
FROM
NBR_LIST_ETL
UNION ALL
SELECT
ID,
SUBSTR(NBR_REMAINING, 1, 3)
AS NBR_SEGMENT,
SUBSTR(NBR_REMAINING, 4)
AS NBR_REMAINING,
NBR_LENGTH - 3
AS NBR_LENGTH
FROM
NBR_FORMAT_RECURSIVE
WHERE
NBR_LENGTH >= 3
)
SELECT
GROUP_CONCAT(NBR_SEGMENT)
AS NBR_FORMATTED
FROM
NBR_FORMAT_RECURSIVE
GROUP BY
ID
If your table contained the following numbers -
NBR
25271
7
29
75438175
342
212
4758
863
2313917
Then the query would output -
NBR_FORMATTED
25,271
7
29
75,438,175
342
212
4,758
863
2,313,917