Get the column names of a query (in own plugin)

Question

Hi,
I'm developing my first plugin. It is a region plugin where the plugin-user passes a sql query as the source that the plugin will turn into a formated report.
I found how to retreive the query result by using APEX_PLUGIN_UTIL.GET_DATA functions. Since it is an array, it is simple to cycle through the data rows. But how can i figure out
1) how many columns the query returns
2) whats the name of the columns is?
Thanks a lot in advance for any hint...
Cheers, Hans

Answer 1

Hi Hans,
the package APEX_PLUGIN_UTIL provides everything you need. No need to do your own DBMS_SQL handling!
Have a look at the API documentation and the example of GET_DATA at http://docs.oracle.com/cd/E23903_01/doc/doc.41/e21676/apex_plugin_util.htm#BABFBIJD
The t_column_value_list record type is a two dimensional array defined as
type t_column_value_list  is table of wwv_flow_global.vc_arr2 index by pls_integer;The first array contains an entry for each column.
l_column_value_list.COUNTcan be used to get the number of columns.
l_column_value_list(1).COUNTcan be used to get the number of rows. An example to iterate over all columns and rows:
for l_column in 1 .. l_column_value_list.count loop
    for l_row in 1 .. l_column_value_list(l_column).count loop
        sys.htp.p('column#=' || l_column || ' row=' || l_row || ' value: ' || l_column_value_list(l_column)(l_row));
    end loop;
end loop;If you need the name of the columns and maybe the original data type and not everything converted to VARCHAR2 you have to use the more sophisticated GET_DATA2. See http://docs.oracle.com/cd/E23903_01/doc/doc.41/e21676/apex_plugin_util.htm#BABFJHAI
This function returns the record type t_column_value_list2 which is defined as
type t_value is record (
    varchar2_value      varchar2(32767),
    number_value        number,
    date_value          date,
    timestamp_value     timestamp,
    timestamp_tz_value  timestamp with time zone,
    timestamp_ltz_value timestamp with local time zone,
    interval_y2m_value  interval year to month,
    interval_d2s_value  interval day to second,
    blob_value          blob,
    bfile_value         bfile,
    clob_value          clob );
type t_value_list is table of t_value index by pls_integer;
type t_column_values is record (
    name       varchar2(32767),
    data_type  varchar2(20), /* use c_data_type_* constants to compare */
    value_list t_value_list );
type t_column_value_list2 is table of t_column_values         index by pls_integer;Again, it's some kind of two dimensional array. The first dimensions are the columns. But this time you also get some details of the parsed column. For example:
for l_column in 1 .. l_column_value_list2.COUNT loop
    sys.htp.p('Column Name: ' || l_column_value_list2(l_column).name || ' Data Type: ' || l_column_value_list2(l_column).data_type );
end loop;Will return you all the columns of the SQL statement. Using "name" and "data_type" you can get the column name and the data type. To access the values you can use
for l_column in 1 .. l_column_value_list2.COUNT loop
    sys.htp.p('Column Name: ' || l_column_value_list2(l_column).name || ' Data Type: ' || l_column_value_list2(l_column).data_type );
    for l_rows in 1 .. l_column_value_list2(l_column).value_list.COUNT loop
        sys.htp.p(
            'row=' || l_row || ' value: ' ||
            apex_plugin_util.get_value_as_varchar2 (
                p_data_type => l_column_value_list2(l_column).data_type,
                p_value     => l_column_value_list2(l_column).value_list(l_row) );
    end loop;
end loop;I used apex_plugin_util.get_value_as_varchar2 to always get a VARCHAR2, independent of the actual data type of the column. If you need the original data type, use "number_value", ... of the t_value record type.
Hope that gives you a direction
Patrick
Regards
Patrick
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