是否可以格式化整数列以使逗号作为Sqlite中的千位数分隔符?我想查询结果如下.
Id Name Price
1 Product1 1,000
2 Product2 2,500
最佳答案 SQLite中没有内置数字格式化功能,但您可以创建一个
user-defined function来创建一个.
这是一个有效的例子.使用整数,需要调整浮点数.
#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));
}