We have One to Many DB2 table with Auto Increment as Default. Both Primary key o

Option (1) will resolve this issue. This happens due to the order in which the items are written to tables in the INSERT transaction.

take a look at the following XSD. XP_Product has one to many XP_Accounts. After publishing the imported CDTS, XP_ACCOUNT table will have a foreign key XP_ID which refers to parent id (primary key). The foreign constraints will be set automatically by the SQL generated by Appian data store verify/publish activity.

<xsd:schema targetNamespace="urn:com:xyz:types:project"
xmlns:cmpo1="urn:com:xyz:types:project" xmlns:xsd="www.w3.org/.../XMLSchema">
<xsd:complexType name="XP_Account">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                    @Table(name="XP_ACCOUNT")
           </xsd:appinfo>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="Id" type="xsd:int">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                                        @Id
                                        @GeneratedValue                                        
                                        @Column(name="ID", nullable=false, columnDefinition="integer")
                     </xsd:appinfo>
<xsd:documentation>Primary key for account table</xsd:documentation>
</xsd:annotation>
</xsd:element>
<xsd:element name="AccountNumber" nillable="true" type="xsd:string">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                                        @Column(name="ACCOUNT_NUMBER", nullable=true, columnDefinition="varchar(20)")
                     </xsd:appinfo>
<xsd:documentation>Holds the Account Number</xsd:documentation>
</xsd:annotation>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="XP_Product">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                    @Table(name="XP_PRODUCT")
           </xsd:appinfo>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="Id" type="xsd:int">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                                        @Id
                                        @GeneratedValue
                                        @Column(name="ID", nullable=false, columnDefinition="integer")
                     </xsd:appinfo>
<xsd:documentation>Unique Product Id - Primary Key. </xsd:documentation>
</xsd:annotation>
</xsd:element>
           <xsd:element maxOccurs="unbounded" minOccurs="0"
name="AccountList" type="tns:XP_Account">
<xsd:annotation>
<xsd:appinfo source="appian.jpa">
                                         @OneToMany(indexed=false)
@JoinColumn(name="XP_ID")
                     </xsd:appinfo>
<xsd:documentation>Request's Account List</xsd:documentation>
</xsd:annotation>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>

Thank You Mike.

Just to add to what Mike has said, I've taken to setting any foreign key to nillable when creating databases for Appian.