Find way for gathering data and replace with values from another table - sql

Question

I am looking for an Oracle SQL query to find a specific pattern and replace them with values from another table.
Scenario:
Table 1:
No column1
-----------------------------------------
12345 user:12345;group:56789;group:6785;...
Note: field 1 may be has one or more pattern
Table2 :
Id name type
----------------------
12345 admin user
56789 testgroup group
Result must be the same
No column1
-----------------------------------
12345 user: admin;group:testgroup

Answer 1

Logic:
First split the concatenated string to individual rows using connect
by clause and regex.
Join the newly created table(split_tab) with Table2(tab2).
Use listagg function to concatenate data in the columns.
Query:
WITH tab1 AS
( SELECT '12345' NO
,'user:12345;group:56789;group:6785;' column1
FROM DUAL )
,tab2 AS
( SELECT 12345 id
,'admin' name
,'user' TYPE
FROM DUAL
UNION
SELECT 56789 id
,'testgroup' name
,'group' TYPE
FROM DUAL )
SELECT no
,listagg(category||':'||name,';') WITHIN GROUP (ORDER BY tab2.id) column1
FROM ( SELECT NO
,REGEXP_SUBSTR( column1, '(\d+)', 1, LEVEL ) id
,REGEXP_SUBSTR( column1, '([a-z]+)', 1, LEVEL ) CATEGORY
FROM tab1
CONNECT BY LEVEL <= regexp_count( column1, '\d+' ) ) split_tab
,tab2
WHERE split_tab.id = tab2.id
GROUP BY no
Output:
No Column1
12345 user:admin;group:testgroup

Answer 2

with t1 (no, col) as
(
-- start of test data
select 1, 'user:12345;group:56789;group:6785;' from dual union all
select 2, 'user:12345;group:56789;group:6785;' from dual
-- end of test data
)
-- the lookup table which has the substitute strings
-- nid : concatenation of name and id as in table t1 which requires the lookup
-- tname : required substitute for each nid
, t2 (id, name, type, nid, tname) as
(
select t.*, type || ':' || id, type || ':' || name from
(
select 12345 id, 'admin' name, 'user' type from dual union all
select 56789, 'testgroup', 'group' from dual
) t
)
--select * from t2;
-- cte table calculates the indexes for the substrings (eg, user:12345)
-- no : sequence no in t1
-- col : the input string in t1
-- si : starting index of each substring in the 'col' input string that needs attention later
-- ei : ending index of each substring in the 'col' input string
-- idx : the order of substring to put them together later
,cte (no, col, si, ei, idx) as
(
select no, col, 1, case when instr(col,';') = 0 then length(col)+1 else instr(col,';') end, 1 from t1 union all
select no, col, ei+1, case when instr(col,';', ei+1) = 0 then length(col)+1 else instr(col,';', ei+1) end, idx+1 from cte where ei + 1 <= length(col)
)
,coll(no, col, sstr, idx, newstr) as
(
select
a.no, a.col, a.sstr, a.idx,
-- when a substitute is not found in t2, use the same input substring (eg. group:6785)
case when t2.tname is null then a.sstr else t2.tname end
from
(select cte.*, substr(col, si, ei-si) as sstr from cte) a
-- we don't want to miss if there is no substitute available in t2 for a substring
left outer join
t2
on (a.sstr = t2.nid)
)
select no, col, listagg(newstr, ';') within group (order by no, col, idx) from coll
group by no, col;