SQL to C: Numeric

Artikkeli
02/28/2023

The identifiers for the numeric ODBC SQL data types are the following:

SQL_DECIMAL
SQL_BIGINT
SQL_NUMERIC
SQL_REAL
SQL_TINYINT
SQL_FLOAT
SQL_SMALLINT
SQL_DOUBLE SQL_INTEGER

The following table shows the ODBC C data types to which numeric SQL data may be converted. For an explanation of the columns and terms in the table, see Converting Data from SQL to C Data Types.

C type identifier	Test	*TargetValuePtr	*StrLen_or_IndPtr	SQLSTATE
SQL_C_CHAR	Character byte length < BufferLength Number of whole (as opposed to fractional) digits < BufferLength Number of whole (as opposed to fractional) digits >= BufferLength	Data Truncated data Undefined	Length of data in bytes Length of data in bytes Undefined	n/a 01004 22003
SQL_C_WCHAR	Character length < BufferLength Number of whole (as opposed to fractional) digits < BufferLength Number of whole (as opposed to fractional) digits >= BufferLength	Data Truncated data Undefined	Length of data in characters Length of data in characters Undefined	n/a 01004 22003
SQL_C_STINYINT SQL_C_UTINYINT SQL_C_TINYINT SQL_C_SBIGINT SQL_C_UBIGINT SQL_C_SSHORT SQL_C_USHORT SQL_C_SHORT SQL_C_SLONG SQL_C_ULONG SQL_C_LONG SQL_C_NUMERIC	Data converted without truncation[a] Data converted with truncation of fractional digits[a] Conversion of data would result in loss of whole (as opposed to fractional) digits[a]	Data Truncated data Undefined	Size of the C data type Size of the C data type Undefined	n/a 01S07 22003
SQL_C_FLOAT SQL_C_DOUBLE	Data is within the range of the data type to which the number is being converted[a] Data is outside the range of the data type to which the number is being converted[a]	Data Undefined	Size of the C data type Undefined	n/a 22003
SQL_C_BIT	Data is 0 or 1[a] Data is greater than 0, less than 2, and not equal to 1[a] Data is less than 0 or greater than or equal to 2[a]	Data Truncated data Undefined	1[b] 1[b] Undefined	n/a 01S07 22003
SQL_C_BINARY	Byte length of data <= BufferLength Byte length of data > BufferLength	Data Undefined	Length of data Undefined	n/a 22003
SQL_C_INTERVAL_MONTH[c] SQL_C_INTERVAL_YEAR[c] SQL_C_INTERVAL_DAY[c] SQL_C_INTERVAL_HOUR[c] SQL_C_INTERVAL_MINUTE[c] SQL_C_INTERVAL_SECOND[c]	Data not truncated Fractional seconds portion truncated Whole part of number truncated	Data Truncated data Undefined	Length of data in bytes Length of data in bytes Undefined	n/a 01S07 22015
SQL_C_INTERVAL_YEAR_TO_MONTH SQL_C_INTERVAL_DAY_TO_HOUR SQL_C_INTERVAL_DAY_TO_MINUTE SQL_C_INTERVAL_DAY_TO_SECOND SQL_C_INTERVAL_HOUR_TO_MINUTE SQL_C_INTERVAL_HOUR_TO_SECOND	Whole part of number truncated	Undefined	Undefined	22015

[a] The value of BufferLength is ignored for this conversion. The driver assumes that the size of *TargetValuePtr is the size of the C data type.

[b] This is the size of the corresponding C data type.

[c] This conversion is supported only for the exact numeric data types (SQL_DECIMAL, SQL_NUMERIC, SQL_TINYINT, SQL_SMALLINT, SQL_INTEGER, and SQL_BIGINT). It is not supported for the approximate numeric data types (SQL_REAL, SQL_FLOAT, or SQL_DOUBLE).

SQL_C_NUMERIC and SQLSetDescField

The SQLSetDescField Function is required to perform manual binding with SQL_C_NUMERIC values. (Note that SQLSetDescField was added in ODBC 3.0.) To perform manual binding, you must first get the descriptor handle.

if (fCType == SQL_C_NUMERIC) {   
   // special processing required for NUMERIC to get right scale & precision  
   // Modify the fields in the implicit application parameter descriptor  
   SQLHDESC hdesc=NULL;  
  
   // Use SQL_ATTR_APP_ROW_DESC for calls to SQLBindCol()  
   // Use SQL_ATTR_APP_PARAM_DESC for calls to SQLBindParameter()  
   //  
   // retcode = SQLGetStmtAttr(hstmt, SQL_ATTR_APP_ROW_DESC, &hdesc, 0, NULL);  
   retcode = SQLGetStmtAttr(hstmt, SQL_ATTR_APP_PARAM_DESC, &hdesc, 0, NULL);  
   if (!ODBC_CALL_SUCCESS(retcode)) {  
      printf ("\nSQLGetStmtAttr failed");  
      i = 1;  
      sqlstate[7] = '\0';  
      while (SQLGetDiagRec(SQL_HANDLE_STMT, hstmt, i, sqlstate, &NativeError, wrkbuf, sizeof(wrkbuf), &len) != SQL_NO_DATA) {  
         printf("\niTestCase = %d Failed...Precision = %d, Scale = %d\nNativeError=%d, State=%s, \n  Message=%s",   
            iTestCase, Precision, Scale, NativeError, sqlstate, wrkbuf);  
         i++;  
      }  
      continue;  
   }  
   retcode = SQLSetDescField(hdesc, iCol, SQL_DESC_TYPE, (SQLPOINTER) SQL_C_NUMERIC, 0);  
   if (!ODBC_CALL_SUCCESS(retcode))  
      goto error;  
   retcode = SQLSetDescField(hdesc, iCol, SQL_DESC_PRECISION, (SQLPOINTER)num.precision, 0);  
   if (!ODBC_CALL_SUCCESS(retcode))  
      goto error;  
   retcode = SQLSetDescField(hdesc, iCol, SQL_DESC_SCALE, (SQLPOINTER)num.scale, 0);  
   if (!ODBC_CALL_SUCCESS(retcode))  
      goto error;  
   retcode = SQLSetDescField(hdesc, iCol, SQL_DESC_DATA_PTR, (SQLPOINTER) &(num), sizeof(num));

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SQL to C: Numeric

SQL_C_NUMERIC and SQLSetDescField

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