define external counter function SQLDescribeCol
     (  read-only SQL_handle_type StatementHandle,
        value counter ColumnNumber,
        modifiable stream ColumnName,
        value counter BufferLength,
        modifiable counter NameLength,
        modifiable counter DataType,
        modifiable counter ColumnSize,
        modifiable counter DecimalDigits,
        modifiable counter Nullable )

Returns the result descriptor, column name, type, precision, scale, and "nullability" for one column in the result set.

Input arguments:

• StatementHandle.
• ColumnNumber. The number of the result set column. Columns are numbered in increasing column order, starting at 0. Column 0 is the bookmark column, if bookmarks are available. Otherwise, column numbers start at 1.
• BufferLength. The maximum length of ColumnName.

Output arguments:

1. ColumnName. The column name. If the column is unnamed or cannot be determined, the driver returns an empty string.
2. NameLength. The returned length of ColumnName.
3. DataType. The SQL data type of the column. The following values are allowed:
   • SQL_UNKNOWN_TYPE
   • SQL_CHAR
   • SQL_NUMERIC
   • SQL_DECIMAL
   • SQL_INTEGER
   • SQL_SMALLINT
   • SQL_FLOAT
   • SQL_REAL
   • SQL_DOUBLE
   • SQL_DATETIME
   • SQL_VARCHAR
   • SQL_TYPE_DATE
   • SQL_TYPE_TIME
   • SQL_TYPE_TIMESTAMP
4. ColumnSize. The size of the column on the data source. If the column size cannot be determined, the driver returns 0.
5. DecimalDigits. The number of decimal digits of the column on the data source. If the number of decimal digits cannot be determined or is not applicable, the driver returns 0.
6. Nullable. Indicates whether the column allows null values. The following values are allowed:
   • SQL_NO_NULLS
   • SQL_NULLABLE
   • SQL_NULLABLE_UNKNOWN