利用DeepSeek采用hugeint转字符串函数完善luadbi-duckdb的decimal处理

用如下函数替换原有同名函数，弥补了原函数不能处理非常大的HUGEINT值的缺陷。让DeepSeek利用已有hugeint转换的字符串，结合scale插入小数点，避免除法运算。

// 将decimal数据转换为字符串
void decimal_to_string_format(uint8_t width, uint8_t scale, void* data, int type, char* buffer, size_t buffer_size) {if (data == NULL || buffer == NULL || buffer_size == 0) {return;}// 根据类型获取整数值int64_t int_value = 0;switch (type) {case DUCKDB_TYPE_TINYINT: // int8_tint_value = *(int8_t*)data;break;case DUCKDB_TYPE_SMALLINT: // int16_tint_value = *(int16_t*)data;break;case DUCKDB_TYPE_INTEGER: // int32_tint_value = *(int32_t*)data;break;case DUCKDB_TYPE_BIGINT: // int64_tint_value = *(int64_t*)data;break;case DUCKDB_TYPE_HUGEINT: // int128_t{duckdb_hugeint huge_val = *(duckdb_hugeint*)data;// 简化处理：如果upper为0，只使用lower部分if (huge_val.upper == 0) {int_value = *(int64_t*)data;break;} else {// 对于非常大的HUGEINT值,用hugeint返回的字符串int128_t u128a = ((int128_t)UINT64_MAX + 1) * huge_val.upper + huge_val.lower;char a[100];int128_to_string_safe(u128a, a, sizeof(a));if (scale == 0) {snprintf(buffer, buffer_size, "%s", a);} else {size_t len = strlen(a);if (scale >= len) {// 小数位数大于等于数字总长度，需要在前面补0// 例如: "123" scale=5 -> "0.00123"snprintf(buffer, buffer_size, "0.%0*s%s", scale - len, "0", a);} else {// 正常情况，在合适位置插入小数点// 例如: "12345" scale=2 -> "123.45"size_t decimal_pos = len - scale;// 复制整数部分strncpy(buffer, a, decimal_pos);// 添加小数点buffer[decimal_pos] = '.';// 复制小数部分strncpy(buffer + decimal_pos + 1, a + decimal_pos, scale);// 添加结束符buffer[len + 1] = '\0';}}}}return;default:// 无效类型snprintf(buffer, buffer_size, "decimal(%d,%d,invalid_type,%d)", width, scale, type);return;}// 处理负号int is_negative = (int_value < 0);uint64_t abs_value = is_negative ? (uint64_t)(-int_value) : (uint64_t)int_value;if (scale == 0) {// 整数情况，直接输出snprintf(buffer, buffer_size, "%s%lu", is_negative ? "-" : "", abs_value);} else {// 计算10^scaleuint64_t divisor = 1;for (int i = 0; i < scale; i++) {divisor *= 10;}// 分离整数部分和小数部分uint64_t integer_part = abs_value / divisor;uint64_t fractional_part = abs_value % divisor;// 构建格式字符串，确保小数部分有正确的位数（前导零）char format[32];snprintf(format, sizeof(format), "%%s%%lu.%%0%dlu", scale);// 格式化输出snprintf(buffer, buffer_size, format, is_negative ? "-" : "", integer_part, fractional_part);}
}

这样改造以后，就可以处理各种大小的decimal数据了，与duckdb的输出一致。

root@66d4e20ec1d7:/par/luadbi# lua ../duck.lua
-15
2025-09-25 12:26:55.123456
-1234567890123456789012345
-12345678900020250922.12345
root@66d4e20ec1d7:/par/luadbi# ../duckdb141 lua_duckdb -c "from table_1"
┌───────┬────────────────────────────┬────────────────────────────┬─────────────────────────────┐
│  id   │          column1           │          column2           │           column3           │
│ int32 │         timestamp          │           int128           │        decimal(34,5)        │
├───────┼────────────────────────────┼────────────────────────────┼─────────────────────────────┤
│  -15  │ 2025-09-25 12:26:55.123456 │ -1234567890123456789012345 │ -12345678900020250922.12345 │
└───────┴────────────────────────────┴────────────────────────────┴─────────────────────────────┘root@66d4e20ec1d7:/par/luadbi# lua ../duck.lua
-15
2025-09-25 12:26:55.123456
-1234567890123456789012345
-345.00000
root@66d4e20ec1d7:/par/luadbi# ../duckdb141 lua_duckdb -c "from table_1"
┌───────┬────────────────────────────┬────────────────────────────┬───────────────┐
│  id   │          column1           │          column2           │    column3    │
│ int32 │         timestamp          │           int128           │ decimal(34,5) │
├───────┼────────────────────────────┼────────────────────────────┼───────────────┤
│  -15  │ 2025-09-25 12:26:55.123456 │ -1234567890123456789012345 │  -345.00000   │
└───────┴────────────────────────────┴────────────────────────────┴───────────────┘root@66d4e20ec1d7:/par/luadbi# lua ../duck.lua
-15
2025-09-25 12:26:55.123456
-1234567890123456789012345
-12345678900.03450
root@66d4e20ec1d7:/par/luadbi# ../duckdb141 lua_duckdb -c "from table_1"
┌───────┬────────────────────────────┬────────────────────────────┬────────────────────┐
│  id   │          column1           │          column2           │      column3       │
│ int32 │         timestamp          │           int128           │   decimal(34,5)    │
├───────┼────────────────────────────┼────────────────────────────┼────────────────────┤
│  -15  │ 2025-09-25 12:26:55.123456 │ -1234567890123456789012345 │ -12345678900.03450 │
└───────┴────────────────────────────┴────────────────────────────┴────────────────────┘

测试脚本如下

DBI = require "DBI"dbd, err = DBI.Connect( 'DuckDB', 'lua_duckdb', 'dbuser', 'password' )
assert(dbd, err)dbd:autocommit(true)
statement = dbd:prepare( "create or replace table table_1 as select -15 id, timestamp'2025-09-25 12:26:55.123456'column1, '-1234567890123456789012345'::hugeint  column2,'-12345678900.0345'::decimal(34,5) column3 ;" )
statement:execute()statement = assert(dbd:prepare( "select * from table_1 where id = $1;" ))
statement:execute( -15 )for row in statement:rows(true) doprint(row['id'])print(row['column1'])print(row['column2'])print(row['column3'])end