rupesh bajaj wrote:
Hi,
Is Like operator can be used to join two relation. If yes what is its use?
And how it is used?
It tests a column for a partial match. So:
'abc' LIKE 'a%' = true
'abc' LIKE 'a_c' = true
'abc' LIKE 'A%' = false
See the manuals for details on other wildcard options and alternative
pattern-matching systems.
You can store the pattern in a column too, though that's less common:
richardh=> SELECT * FROM targets;
tgt
-----------
abc123def
ghi123def
(2 rows)
richardh=> SELECT * FROM patterns;
patt
-------
abc%
%123%
(2 rows)
richardh=> SELECT tgt,count(*) FROM targets, patterns
WHERE tgt LIKE patt GROUP BY tgt ORDER BY tgt;
tgt | count
-----------+-------
abc123def | 2
ghi123def | 1
(2 rows)
HTH
--
Richard Huxton
Archonet Ltd
