How to retreive the max data length of a column

Question

Hello All,
I know how to do a select to get the max data length of a column it is this :
SELECT MAX(LENGTH(COLUMN_NAME) FROM table.
However, I need this information combined with my SQL that returns the Data_type and length from the USER_TAB_COLUMNS. So taking the emp example if the ename column was 50 as VARCHAR2 but the max data entered in it was just 20 I want the information like this:
SELECT COLUMN_NAME, DATA_LENGTH, and the Max length of 20
FROM USER_TAB_COLUMNS WHERE TABLE_NAME='EMP';
I don't know how to get the Max Length of the Column in this table. Can anyone suggest me a hint? An Inline view maybe?
Thanks

Answer 1

Still not sure about your requirements, but how about this
SQL> CREATE OR REPLACE FUNCTION get_max_length(p_table in varchar2, p_col in varchar2) return pls_integer
  2  is
  3    v_cnt pls_integer;
  4  begin
  5    execute immediate 'select max(length('||p_col||')) from '||p_table into v_cnt;
  6    return v_cnt;
  7  end get_max_length;
  8  /
Function created.
SQL>
SQL> SELECT COLUMN_NAME,
  2         DATA_LENGTH,
  3         get_max_length(TABLE_NAME, COLUMN_NAME) max_length
  4  FROM USER_TAB_COLUMNS
  5  WHERE TABLE_NAME='EMP'
  6  AND DATA_TYPE like '%CHAR%'
  7  ;
COLUMN_NAME                    DATA_LENGTH MAX_LENGTH
ENAME                                   10          6
JOB                                      9          9
SQL>