Null Pointer Exception when an untyped NULL subquery ("values null") appears outside of the FROM list in a SELECT query.

• Key: DERBY-2218
• Type: Bug
• Status: Closed
• Resolution: Fixed
• Priority: Minor
• Assignee: Yip Ng
• Reporter: A B
• Component/s: SQL
• Affects Version/s: 10.1.3.2, 10.2.2.1, 10.2.3.0, 10.3.1.4
• Fix Version/s: 10.2.2.1, 10.2.3.0, 10.3.1.4

Description

If a SELECT query contains a subquery which includes an untyped NULL value at any place other than in the FROM list, Derby will throw an NPE at bind time.

ij> create table t1 (i int);
0 rows inserted/updated/deleted

-- If the untyped NULL is in the FROM list, a reasonable error is thrown.

ij> select * from (values null) x;
ERROR 42X07: Null is only allowed in a VALUES clause within an INSERT statement.

ij> select * from (select * from t1, (values null) x )y;
ERROR 42X07: Null is only allowed in a VALUES clause within an INSERT statement.

-- But if it appears anywhere else, the result is an NPE:

-- IN-list
ij> select * from t1 where i in (1, 2, (values null));
ERROR XJ001: Java exception: ': java.lang.NullPointerException'.

-- where clause
select * from t1 where (values null);

-- order by clause
select * from t1 order by (values null);

-- result column
select (values null) from t1;

-- group by clause (only works in 10.2 and later)
select * from t1 group by (values null);

-- having clause
select * from t1 group by i having (values null);

Stack trace (from 10.2.2) is:

java.lang.NullPointerException
at org.apache.derby.impl.sql.compile.SubqueryNode.setDataTypeServices(SubqueryNode.java:2289)
at org.apache.derby.impl.sql.compile.SubqueryNode.bindExpression(SubqueryNode.java:529)
at org.apache.derby.impl.sql.compile.ValueNodeList.bindExpression(ValueNodeList.java:130)
at org.apache.derby.impl.sql.compile.BinaryListOperatorNode.bindExpression(BinaryListOperatorNode.java:161)
at org.apache.derby.impl.sql.compile.SelectNode.bindExpressions(SelectNode.java:540)
at org.apache.derby.impl.sql.compile.DMLStatementNode.bindExpressions(DMLStatementNode.java:249)
at org.apache.derby.impl.sql.compile.DMLStatementNode.bind(DMLStatementNode.java:162)
at org.apache.derby.impl.sql.compile.CursorNode.bind(CursorNode.java:253)
at org.apache.derby.impl.sql.GenericStatement.prepMinion(GenericStatement.java:345)
at org.apache.derby.impl.sql.GenericStatement.prepare(GenericStatement.java:119)