Submitted by: @cincuranet

Votes: 2

I get error message "Failed to merge object(s).
Object reference not set to an instance of an object.

I use DDXE and Data Designer. I try moved tables from Server Explorer to Data Designer. I attach simple database. I can`t add TAB6 to data designer. When I remove constraints, I can move table.

create table TAB1
(
TAB1_ID NUMERIC(18) not null,
TAB_TEXT VARCHAR(120) ,
constraint PK_TAB1 primary key (TAB1_ID)
);

create table TAB2
(
TAB2_ID NUMERIC(16) not null,
TAB1_ID NUMERIC(18) ,
TAB2_TEXT VARCHAR(120) ,
constraint PK_TAB2 primary key (TAB2_ID)
);

create table TAB4
(
TAB4_ID NUMERIC(16) not null,
TAB1_ID NUMERIC(18) ,
TAB4_N4 NUMERIC(4) ,
constraint PK_TAB4 primary key (TAB4_ID)
);

create table TAB3
(
TAB3_ID NUMERIC(18) not null,
TAB2_ID NUMERIC(18) ,
TAB3_N3 NUMERIC(3) ,
constraint PK_TAB3 primary key (TAB3_ID)
);

create table TAB5
(
TAB5_ID NUMERIC(18) not null,
TAB2_ID NUMERIC(18) ,
TAB4_ID NUMERIC(16) ,
TAB5_I INTEGER ,
constraint PK_TAB5 primary key (TAB5_ID)
);

create table TAB6
(
TAB6_ID NUMERIC(16) not null,
TAB5_ID NUMERIC(18) ,
TAB3_ID NUMERIC(18) ,
TAB6_N18_4 NUMERIC(18,4) ,
constraint PK_TAB6 primary key (TAB6_ID)
);

alter table TAB2
add constraint FK_TAB2_TAB1_TAB2_TAB1 foreign key (TAB1_ID)
references TAB1;

alter table TAB4
add constraint FK_TAB4_RELATION__TAB1 foreign key (TAB1_ID)
references TAB1;

alter table TAB3
add constraint FK_TAB3_RELATION__TAB2 foreign key (TAB2_ID)
references TAB2;

alter table TAB5
add constraint FK_TAB5_RELATION__TAB2 foreign key (TAB2_ID)
references TAB2;

alter table TAB5
add constraint FK_TAB5_RELATION__TAB4 foreign key (TAB4_ID)
references TAB4;

alter table TAB6
add constraint FK_TAB6_RELATION__TAB5 foreign key (TAB5_ID)
references TAB5;

alter table TAB6
add constraint FK_TAB6_RELATION__TAB3 foreign key (TAB3_ID)
references TAB3;