Preventing sqlplus truncation of column names, without individual column formatting

Question

By default sqlplus truncates column names to the length of the underlying data type. Many of the column names in our database are prefixed by the table name, and therefore look

Answer 1

This should provide some reasonable formatting. You are, of course, free to substitute your own preferences for the maximum width of char columns, and what to do with LONG, RAW and LOB columns.

SELECT 'COLUMN ' || column_name || ' FORMAT ' ||
       CASE
          WHEN data_type = 'DATE' THEN
           'A9'
          WHEN data_type LIKE '%CHAR%' THEN
           'A' ||
           TRIM(TO_CHAR(LEAST(GREATEST(LENGTH(column_name),
                        data_length), 40))) ||
           CASE
              WHEN data_length > 40 THEN
               ' TRUNC'
              ELSE
               NULL
           END
          WHEN data_type = 'NUMBER' THEN
           LPAD('0', GREATEST(LENGTH(column_name),
           NVL(data_precision, data_length)), '9') ||
           DECODE(data_scale, 0, NULL, NULL, NULL, '.' ||
           LPAD('0', data_scale, '0'))
          WHEN data_type IN ('RAW', 'LONG') THEN
           'A1 NOPRINT'
          WHEN data_type LIKE '%LOB' THEN
           'A1 NOPRINT'
          ELSE
           'A' || TRIM(TO_CHAR(GREATEST(LENGTH(column_name), data_length)))
       END AS format_cols
  FROM dba_tab_columns
 WHERE owner = 'SYS'
   AND table_name = 'DBA_TAB_COLUMNS';