Retrieve records from a specific column in oracle

问题

S.NO     id        Pid
1        123       PAQ123  
2        433       WSD3FF  
3        565       PAS45E  
4        123       PAQ123X  
5        433       WSD3FFY  
6        123       PAQ123Z

suppose the above is the sample records in the database.

Now I want to find out in the database whether there is any word (example PAQ123) which is repeating with some prefixes/suffixes like in (PAQ123X,PAQ123Z).

How can I write a query which would result into the above list scenario?

回答1:

Oracle Setup:

CREATE TABLE table_name ( S_NO, id, Pid ) AS
SELECT 1, 123, 'PAQ123' FROM DUAL UNION ALL
SELECT 2, 433, 'WSD3FF' FROM DUAL UNION ALL  
SELECT 3, 565, 'PAS45E' FROM DUAL UNION ALL
SELECT 4, 123, 'PAQ123X' FROM DUAL UNION ALL
SELECT 5, 433, 'WSD3FFY' FROM DUAL UNION ALL
SELECT 6, 123, 'PAQ123Z' FROM DUAL;

Query:

SELECT *
FROM   (
  SELECT t.*,
         ( SELECT COUNT(*)
           FROM   table_name x
           WHERE  t.id = x.id
           AND    LENGTH( t.Pid ) < LENGTH( x.pid )
           AND    INSTR( x.Pid, t.Pid ) = 1 ) AS num_matches
  FROM   Table_name t
)
WHERE num_matches > 0;

Output:

      S_NO         ID PID     NUM_MATCHES
---------- ---------- ------- -----------
         1        123 PAQ123            2 
         2        433 WSD3FF            1 

If you want to get the matches then you can use a collection:

CREATE TYPE stringlist AS TABLE OF VARCHAR2(100);
/

Query:

SELECT *
FROM   (
  SELECT t.*,
         CAST(
           MULTISET(
             SELECT PID
             FROM   table_name x
             WHERE  t.id = x.id
             AND    LENGTH( t.Pid ) < LENGTH( x.pid )
             AND    INSTR( x.Pid, t.Pid ) = 1
           )
           AS stringlist
         ) AS matches
  FROM   Table_name t
)
WHERE matches IS NOT EMPTY;

or (since I'm not sure MULTISET is in 10g):

SELECT *
FROM   (
  SELECT t.*,
         CAST(
           ( 
             SELECT COLLECT( PID )
             FROM   table_name x
             WHERE  t.id = x.id
             AND    LENGTH( t.Pid ) < LENGTH( x.pid )
             AND    INSTR( x.Pid, t.Pid ) = 1
           )
           AS stringlist
         ) AS matches
  FROM   Table_name t
)
WHERE matches IS NOT EMPTY;

Output

      S_NO         ID PID     MATCHES 
---------- ---------- ------- ------------------------------------
         1        123 PAQ123  TEST.STRINGLIST('PAQ123X','PAQ123Z')
         2        433 WSD3FF  TEST.STRINGLIST('WSD3FFY')

来源：https://stackoverflow.com/questions/36704056/retrieve-records-from-a-specific-column-in-oracle