Question

I am facing a problem using XMLAGG in sql.

I have a table with multiple records which can be repeated. the Table contains Customer Addresses and Customer Name.

Create Table cust_data(
    cust_name varchar2(30),
    cust_addr_line1 varchar2(300),
    cust_addr_line2 varchar2(300),
    cust_addr_line3 varchar2(300),
    cust_addr_type varchar2(3));

The table may contain multiple records for a Single Customer Name and Different Address Types.

Also, a single customer may have multiple addresses of the same type also.

so a customer may have addresses like

cust1 address1 curr_address
cust1 address2 old_address
cust1 address3 old_address
cust1 address4 old_address
cust2 address5 curr_address
cust2 address6 old_address

I have a select where i want to take out all the customer names with old_addresses in a comma separated format.

using the same i used the following sql

 select XMLAGG(XMLELEMENT(E, cust_name || ',')).EXTRACT('//text()')
 from cust_data where cust_addr_type ='old_address';

I get the following output:

cust1,cust1,cust1,cust2,

how do get the output as

cust1,cust2

Please help.

Edit#1:

The other tables can be taken like this:

Create Table cust_info(
    cust_name varchar2(30),
    Cust_account varchar2(300),
    cust_amount_paid varchar2(300),
    cust_amount_pend varchar2(300),
    cust_payment_type varchar2(300));

Create Table payment_master_info(
    pmnt_type varchar2(30),
    pmnt_desc varchar2(300),
    pmnt_rate varchar2(300),
    pmnt_tenure varchar2(300));

The query is like this:

SELECT XMLAGG(XMLELEMENT(E, CUST_NAME || ',')) .EXTRACT('//text()'),
             CD.CUST_ADDR_LINE1,
             CD.CUST_ADDR_LINE2,
             CD.CUST_ADDR_LINE3,
             CI.CUST_AMOUNT_PAID,
             CI.CUST_AMOUNT_PEND,
             CI.CUST_ACCOUNT
    FROM CUST_INFO CI, PAYMENT_MASTER_INFO PM, CUST_DATA CD
 WHERE CD.CUST_NAME = CI.CUST_NAME
     AND CI.CUST_PAYMENT_TYPE = PM.PMNT_TYPE
     AND CUST_ADDR_TYPE = 'old_address';

Now the data in this huge. the data in the pmnt_type ranges from 10000-15000 data
and in other tables it ranges from 2100000-5000000

If I apply inner queries for distinct data, the performance drops exponentially.

is there any other way?

Edit#2: Also while using this inner query, during executing, i getting an ORA-19011(: Character string buffer too small.) error. can there be any reason why…??

Answer 1

You can use a DISTINCT in an inner query:

SQL> select XMLAGG(XMLELEMENT(E, cust_name || ',')).EXTRACT('//text()')
  2   from (SELECT distinct cust_name, cust_addr_type FROM cust_data)
  3  where cust_addr_type ='old_address';

XMLAGG(XMLELEMENT
-----------------
cust1,cust2,