Using descriptors

Use descriptor functions to streamline operations.

odbc SQLGetStmtAttr $hstmt SQL_ATTR_APP_ROW_DESC \
    hdesc 32 StringLength
odbc SQLGetDescField $hdesc 0 SQL_DESC_ALLOC_TYPE \
    Value 512 StringLength
odbc SQLGetDescRec $hdesc $RecNumber Name 512 \
    StringLength Type SubType Length Precision Scale Nullable
odbc SQLCopyDesc $hdesc1 $hdesc2
odbc SQLCopyDesc $hdesc1 $hdesc2