Record in table [tableName] already exists - Parent and child tables

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Posted on by Alzack18

Hi!

I have problem with unique values in table.

I have 2 tables:

Parent Table:

table 50900 ParentTable
{
    Caption = 'Parent Table';
    DataClassification = ToBeClassified;

    fields
    {
        field(1; "Parent No."; integer)
        {
            Caption = 'No.';
            DataClassification = ToBeClassified;
        }
        field(2; "Parent Name"; Text[10])
        {
            Caption = 'Parent name';
            DataClassification = ToBeClassified;
        }
    }
    keys
    {
        key(PK; "Parent No.")
        {
            Clustered = true;
        }
    }
}

Child table:

table 50901 ChildTable
{
    Caption = 'Child table';
    DataClassification = ToBeClassified;

    fields
    {
        field(1; "Parent No."; Integer)
        {
            Caption = 'Parent No.';
            DataClassification = ToBeClassified;
            TableRelation = ParentTable."Parent No.";
        }
        field(2; "Child Name"; Text[20])
        {
            Caption = 'Child Name';
            DataClassification = ToBeClassified;
       }
    }
    keys
    {
        key(PK; "Parent No.")
        {
        }
    }
}

I want relation between this two tables one-2-many : ParentTable-2-ChildTable.

When I try to insert second record to ChildTable i get error "The record in table ChildTable already exists. Identification fields and values: Parent No..='1'.

I think that problem is with key on child table. I tried to set property Unique = false, but it didn't help.

Record in tables should look like this:
PARENT:
1;John
2;Emily

CHILD:
1;Emma
1;Lily
2; Steve
2;Patrick

Any solutions?

Best regards.

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DAnny3211 11,423 Super User 2026 Season 1 on at

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Hi

the child table key should be

keys

{

key(PK; "Parent No.;, "Child Name")

{

}

}

check my answer if it helped you, thanks

DAniele

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pankaj.k 1,020 on at

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Hi Alzack,

Customization for Child Table:

you need to add one more filed "Line No." data type must be Integer.

add "Line No." in Primary key. key(PK; "Parent No.","Line No.")

that will resolve your problem.

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YUN ZHU 102,857 Super User 2026 Season 2 on at

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Hi Alzack18, I like your profile image.

As mentioned by other experts, for Child table, you need to add another field as part of its primary key.

You can find some examples in the standard.

Ship-to Address (222): In addition to Customer No., there is also a Code field, and these two form a primary key. This way no errors will occur.

Hope this helps as well.

Thanks.

ZHU

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Alzack18 67 on at

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Thank you all for response!

Problem solved. I added new field "Line Num". Now the pair of these fields is always unique and does not generate a problem :)

My PK looks like this:

key(PK; "Parent No.", "Line Num"){}

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