Inconsistent datatypes: expected NUMBER got CHAR error

Question

Hi,
I have the following table
create GLOBAL TEMPORARY TABLE br_total_rtn_data_tmp
code varchar(50)     NOT NULL,
name                         varchar(255),     
cum_ytd_rtn_amt          varchar(255),     
cum_one_mon_rtn_amt          varchar(255)     ,
cum_thr_mon_rtn_amt          varchar(255)     ,
cum_six_mon_rtn_amt          varchar(255),
cum_nine_mon_rtn_amt     varchar(255),
cum_one_yr_rtn_amt          varchar(255),
cum_thr_yr_rtn_amt          varchar(255),
cum_five_yr_rtn_amt          varchar(255),
cum_ten_yr_rtn_amt          varchar(255),
cum_lof_rtn_amt               varchar(255),
avg_anl_one_yr_rtn_amt     varchar(255),
avg_anl_thr_yr_rtn_amt     varchar(255),
avg_anl_five_yr_rtn_amt     varchar(255),
avg_anl_ten_yr_rtn_amt     varchar(255),
avg_anl_lof_rtn_amt          varchar(255),
cum_prev_1m_month_end     varchar(255),
cum_prev_2m_month_end     varchar(255)
)ON COMMIT PRESERVE ROWS;
I have a case statement
CASE
             WHEN code = 'MDN' THEN
                       max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.mdn /100  else null end)
             WHEN code = 'QRT' THEN
                  max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.quartile  else null end)
             WHEN code = 'PCT' THEN
                  max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.pct_beaten / 100 else null end)
             WHEN code = 'RNK' THEN
                       case when (p.m_date = v_prev2_yr_mon and p.period_type = '1M'  and p.rank is  null and p.cnt is null)
                    THEN
                                   P.RANK
                    else
                                    p.rank||'/'||p.cnt
                    end           
             ELSE NULL
             END CASE The output for code = RNK should be somewhat like 3/5 which is rank/count
but i get the error "Inconsistent datatypes: expected NUMBER got CHAR error" when i put p.rank||'/'||p.cnt
How can that be solved.
ORacle version is 10g.

Answer 1

Taken from the documentation of the CASE expression:
"For a simple CASE expression, the expr and all comparison_expr values must either have the same datatype (CHAR, VARCHAR2, NCHAR, or NVARCHAR2, NUMBER, BINARY_FLOAT, or BINARY_DOUBLE) or must all have a numeric datatype. If all expressions have a numeric datatype, then Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that datatype, and returns that datatype.
For both simple and searched CASE expressions, all of the return_exprs must either have the same datatype (CHAR, VARCHAR2, NCHAR, or NVARCHAR2, NUMBER, BINARY_FLOAT, or BINARY_DOUBLE) or must all have a numeric datatype. If all return expressions have a numeric datatype, then Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that datatype, and returns that datatype."
You need to use the same data type for all your expressions. If you want to return a string, then you need to convert the remaining numbers explicitly to strings. E.g. you could try something like this:
CASE
             WHEN code = 'MDN' THEN
                       to_char(max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.mdn /100  else null end), 'TM')
             WHEN code = 'QRT' THEN
                  to_char(max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.quartile  else null end), 'TM')
             WHEN code = 'PCT' THEN
                  to_char(max(case when p.m_date = v_prev2_yr_mon and p.period_type = '1M' then p.pct_beaten / 100 else null end), 'TM')
             WHEN code = 'RNK' THEN
                       case when (p.m_date = v_prev2_yr_mon and p.period_type = '1M'  and p.rank is  null and p.cnt is null)
                    THEN
                                   to_char(P.RANK, 'TM')
                    else
                                    p.rank||'/'||p.cnt
                    end           
             ELSE NULL
             END CASE I see another potential issue, you're mixing aggregate functions with non-aggregate expressions, this can only work if these non-aggregate expressions are part of the group by clause, but you haven't posted the complete statement so I can only guess.
Regards,
Randolf
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