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From "Milosz Tylenda (JIRA)" <>
Subject [jira] Commented: (OPENJPA-976) Research the need for escape charaters for LIKE in various DB's
Date Tue, 19 May 2009 12:48:45 GMT


Milosz Tylenda commented on OPENJPA-976:

Mike, I think we got a bit off-topic in this issue. I suggest that the outcome of this issue
be a list of databases which gives answers to:

- does the database require ESCAPE [char] clause in LIKE?
- if the databse does not require the ESCAPE clause: does it assume some default escaping
char or does not it do any escaping at all?
- does the database poses any constraints on the escaping chracters? E.g. a back-slash must
be prefixed with another back-slash.

If we got the list, we modify the code (possibly in a new JIRA issue) for the case when a
JPQL string does not specify ESCAPE char:
- we don't generate ESCAPE clause for databases that don't require it
- possibly we could think of what to do if a database happens to assume some default escaping
char (maybe there is no such database)

We might also need to think of the case when a JPQL string specifies ESCAPE char but the database
poses a constraint, e.g. the double back-slash (another JIRA issue).

This is how I understand the problem raised here and in OPENJPA-975. Maybe it is too much
and for the beginning we want to do only a subset of the changes.

As for the list of databases, I can say PostgreSQL does not require ESCAPE so it looks like
Oracle is not alone in their camp.

> Research the need for escape charaters for LIKE in various DB's
> ---------------------------------------------------------------
>                 Key: OPENJPA-976
>                 URL:
>             Project: OpenJPA
>          Issue Type: Improvement
>          Components: jdbc
>            Reporter: B.J. Reed
>            Assignee: B.J. Reed
>            Priority: Minor
>         Attachments: OPENJPA-976.patch
>   Original Estimate: 0h
>  Remaining Estimate: 0h
> A new requiresSearchStringEscapeForLike field was added to the DBDictionary in
 Currently, the default is true and the OracleDictionary overwrites it to false.  Need to
investigate other DB's to see what other dictionaries would be better off as false..

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