Referential integrity: it was not allowed to delete a row with NULL in the…

Referential integrity: it was not allowed to delete a row with NULL in the parent table, if there was a row with NULL in the child table.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,9 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Experimental feature to support case sensitive catalog names
+<ul><li>Referential integrity: it was not allowed to delete a row with NULL in the parent table,
+    if there was a row with NULL in the child table.
+</li><li>Experimental feature to support case sensitive catalog names
     and database names using the DATABASE() method.
     To use this feature, set the system property h2.databaseToUpper to false.
     The plan is to set the property to false by default in version 1.3.x.

h2/src/main/org/h2/constraint/ConstraintReferential.java

@@ -370,6 +370,9 @@ public class ConstraintReferential extends Constraint {
             int refIdx = refCol.getColumnId();
             Column col = columns[i].column;
             Value v = col.convert(oldRow.getValue(refIdx));
+            if (v == ValueNull.INSTANCE) {
+                return;
+            }
             check.setValue(col.getColumnId(), v);
         }
         // exclude the row only for self-referencing constraints

h2/src/test/org/h2/test/test-1.2.txt

 --- special grammar and test cases ---------------------------------------------------------------------------------------------
+create table a(x int, y int);
+> ok
+
+create unique index a_xy on a(x, y);
+> ok
+
+create table b(x int, y int, foreign key(x, y) references a(x, y));
+> ok
+
+insert into a values(null, null), (null, 0), (0, null), (0, 0);
+> update count: 4
+
+insert into b values(null, null), (null, 0), (0, null), (0, 0);
+> update count: 4
+
+delete from a where x is null and y is null;
+> update count: 1
+
+delete from a where x is null and y = 0;
+> update count: 1
+
+delete from a where x = 0 and y is null;
+> update count: 1
+
+delete from a where x = 0 and y = 0;
+> exception
+
+drop table b;
+> ok
+
+drop table a;
+> ok
+
 select * from (select null as x) where x=1;
 > X
 > -

h2/src/test/org/h2/test/testSimple.in.txt

+create table a(id int) as select null;
+create table b(id int references a(id)) as select null;
+delete from a;
+drop table a, b;
 create table test(a int, b int) as select 2, 0;
 create index idx on test(b, a);
 select count(*) from test where a in(2, 10) and b in(0, null);