[Hibernate-issues] [Hibernate-JIRA] Created: (HB-363) Constraint.java does not support CascadeConstraintsString

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Here is an overview of the issue:
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        Key: HB-363
    Summary: Constraint.java does not support CascadeConstraintsString
       Type: Bug

     Status: Unassigned
   Priority: Major

    Project: Hibernate2
 Components: 
             core
   Versions:
             2.1 beta 3

   Assignee: 
   Reporter: ron lussier

    Created: Thu, 25 Sep 2003 1:38 PM
    Updated: Thu, 25 Sep 2003 1:38 PM
Environment: Mac OS X, Frontbase

Description:
In order to properly support SQL92, a change is required to allow the 'alter table ... drop constraint' statement to take a drop behavior.  This change affects net.sf.hibernate.mapping.Constraint.java, line 43.  I would like the line to read:

   return "alter table " + getTable().getQualifiedName(dialect) +
          " drop constraint " + getName() +
          dialect.getCascadeConstraintsString();

Frontbase (the dialect I contributed) requires either 'CASCADE' or 'RESTRICT' in a drop constraint clause.  (Frontbase is VERY SQL/92 standard, sometimes annoyingly.)  Isn't this what the dialect.getCascadeConstraintsString() property is for?  (The documentation for the property reads 'Completely optional cascading drop clause'.)

According to the documentation for SQL/92 (from http://www.contrib.andrew.cmu.edu/~shadow/sql/sql2bnf.aug92.txt), the syntax should be:

   <alter table statement> ::=
       ALTER TABLE <table name> <alter table action>

   <alter table action> ::=
         <add column definition>
       | <alter column definition>
       | <drop column definition>
       | <add table constraint definition>
       | <drop table constraint definition>

   <drop table constraint definition> ::=
       DROP CONSTRAINT <constraint name> <drop behavior>

   <drop behavior> ::= CASCADE | RESTRICT

The requirement of CASCADE or RESTRICT is also affirmed in "A Guide to the SQL Standard", Fourth Edition, on page 106, where the syntax is given as:

   base-table-alteration
      ::= ALTER TABLE base-table base-table-alteration-action

   base-table-alteration-action
      ::=   column-alteration-action
            | base-table-constraint-alteration-action

   base-table-constraint-alteration-action
      ::=    ADD base-table-constraint-definition
            | DROP CONSTRAINT constraint { RESTRICT | CASCADE }

On page 38 of the same volume, under 'Notation', the book states "Braces '{' and '}' are used to indicate that the material enclosed in those braces consists of a set of two or more items (separated by vertical bars) from which exactly one is to be chosen.

If you would prefer, I would be fine with creating a new, optional property of Dialect.java for this purpose, but I think that Hibernate needs something.



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