When we create a table, we can specify the maximum field length, for example:

varchar(25)

How to find out this maximum length?

    2 answers 2

     select column_name, data_type, data_length from all_tab_columns where table_name='имя таблицы' and column_name='имя столбца'; 
       select column_name, data_type, data_precision, data_scale, char_length, char_used from user_tab_columns where table_name = upper('table_name') ;

      Where:

      • data_precision , data_scale - max. number of digits before and after the decimal point for numeric types, null if not specified.
      • char_length , char_used - max. the length of character fields and in what units it is measured, char or byte .