Oracle SQL procedure with table name as input using dynamic SQL - sql

Question

I see a lot of similar questions already answered including here, here and here. The list goes on.
What makes mine different? These other questions seem to be very simple, one line sql statements. I have a more complex merge statement that spans multiple lines and no matter how I have tried to put the statement together it gives me a compilation error. Below is one such attempt.
It is a long statement, the only dynamic parts are 2 nonconsecutive lines at the very beginning as shown below. I have tried to make the whole statement a string and execute it, but I get an error that the string is too long, plus this makes it very hard to read so it is undesirable. I have also tried breaking up the 2 parts that require dynamic sql into 2 execute immediate blocks, but that throws a compilation error as well.
My code
create or replace procedure table_sync(
table_name in varchar2,
source_node in varchar2
)
is
begin
execute immediate
'merge into ' || table_name || ' dest' /* ---- first line ---- */
using (select date_time, version_date, data_entry_date, value
'from username.' || table_name || '#' || source_node /* ---- second line ---- */
where data_entry_date < (sysdate - 10)) src
on ( dest.date_time = src.date_time and
dest.version_date = src.version_date
)
when matched then
update
set
dest.data_entry_date = src.data_entry_date,
dest.value = src.value
where
(case
.
.
.
Is there a way to put combine this dynamic statement?
Thank you

Answer 1

Using merge to achieve this is a good approach, but your statement is missing some quotes. Here is a fiddle with an example, similar to what you are trying to do.
From that fiddle, create test data:
create table table1(id varchar2(30), username varchar2(30), fullname varchar2(30));
create table table2(id varchar2(30), username varchar2(30), fullname varchar2(30));
insert into table1 values('a1', 'b1', 'c1');
insert into table1 values('a2', 'b2', 'c2');
insert into table1 values('a3', 'b3', 'c3');
insert into table1 values('a4', 'b4', 'c4');
insert into table2 values('a1', 'b1', 'c1');
insert into table2 values('a2', 'b2', 'c2');
insert into table2 values('a3', 'b3', 'c3');
Your function:
CREATE OR replace PROCEDURE Table_sync(table_name IN VARCHAR2)
IS
stmnt CLOB;
BEGIN
stmnt := 'merge into ' || table_name || ' dest '
|| 'using (select id, username from table1) src '
|| 'on (dest.id = src.id) '
||
' when matched then update set dest.fullname = src.username || src.id '
|| ' where dest.username like ''%2'' '
|| ' when not matched then insert (id, username, fullname) values(src.id, src.id||src.username, src.username||src.username) '
;
EXECUTE IMMEDIATE stmnt;
END table_sync;
If the record in table1 exists with the same value in col1 as the column in table2, then it will update it based on a condition, if the record does not exist, it will insert it.
You can write all your conditions inside that where statement and pay attention to the 2xsingle quotes used for quoting values in the dynamic query.