Probably a simple SQL Query - Newbie

Question

I want to select entries from a table that has 2 columns where the first column value is contained within the 2 column....Does that make sense?
The first is a varchar that contains a value for a customer. The second is a varchar that contains a a textual description of a problem the customer has. My problem is that I only want to select the entries in the table where the second column contains a description that includes the first column value.
eg. I want to select rows that have the following condition:
column1 has value of "customer1"
column2 has a value of "an error was reported by customer1 on service blah"
but not these
column1 has value of "customer1"
column2 has a value of "an error was reported by customer2 on service blah"
This is probably a simple question but I've spent time looking at how to do it and can't seem to manage...any help would be appreciated....Thanks

Answer 1

Hi Barbara,
I've never used the CONTAINS operator before. I compared the use in this situation to the other methods and found the others to be FAR less resource intensive, despite working on unindexed columns, as I demonstrate below.
It would seem that CONTAINS is unsuited to this type of simple query. Can you shed any light on this, from the perspective of somebody who has used it before? Is this type of performance penalty normal? If so, it could seem that CONTAINS is fairly useless next to LIKE.
[email protected]> desc test;
Name                                        Null?    Type
COLUMN1                                              VARCHAR2(20)
COLUMN2                                              VARCHAR2(100)
[email protected]> select count(*) from test;
  COUNT(*)
     10000
Elapsed: 00:00:00.00
[email protected]> select * from test where instr(column2, column1) > 0;
10000 rows selected.
Elapsed: 00:00:00.18
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=23 Card=8328 Bytes=532992)
   1    0   TABLE ACCESS (FULL) OF 'TEST' (TABLE) (Cost=23 Card=8328 Bytes=532992)
Statistics
          5  recursive calls
          0  db block gets
        821  consistent gets
          0  physical reads
          0  redo size
     702263  bytes sent via SQL*Net to client
       7838  bytes received via SQL*Net from client
        668  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
      10000  rows processed
[email protected]> select * from test where column2 like '%'||column1||'%';
10000 rows selected.
Elapsed: 00:00:00.18
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=23 Card=8328 Bytes=532992)
   1    0   TABLE ACCESS (FULL) OF 'TEST' (TABLE) (Cost=23 Card=8328 Bytes=532992)
Statistics
          5  recursive calls
          0  db block gets
        821  consistent gets
          0  physical reads
          0  redo size
     702263  bytes sent via SQL*Net to client
       7838  bytes received via SQL*Net from client
        668  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
      10000  rows processed
[email protected]> create index testidx on test(column2) indextype is ctxsys.context;
Index created.
[email protected]> select * from test where contains(column2, column1) > 0;
10000 rows selected.
Elapsed: 00:00:56.80
Execution Plan
   0      SELECT STATEMENT Optimizer=ALL_ROWS (Cost=25008 Card=4 Bytes=284)
   1    0   TABLE ACCESS (FULL) OF 'TEST' (TABLE) (Cost=25008 Card=4 Bytes=284)
Statistics
      55201  recursive calls
          0  db block gets
      85857  consistent gets
          0  physical reads
          0  redo size
     702263  bytes sent via SQL*Net to client
       7838  bytes received via SQL*Net from client
        668  SQL*Net roundtrips to/from client
        204  sorts (memory)
          0  sorts (disk)
      10000  rows processedThanks in advance,
Anthony