how can I design a table to get unique values in a column within the PK
columns?
Example:
Client (int, PK)
User (int, PK
Userid(char...)

userid's shoud be unique for a client. Other clients are allowed to have
same userid's as other clients. A second user of a client cannot have the
same userid as other user of this client.

thanks for any help.

Looks like you have it almost right:

alter table MyTable
add
    constraint PK_MyTable primary key (ClientID, UserID)

how can I design a table to get unique values in a column within the PK
columns?
Example:
Client (int, PK)
User (int, PK
Userid(char...)

userid's shoud be unique for a client. Other clients are allowed to have
same userid's as other clients. A second user of a client cannot have the
same userid as other user of this client.

thanks for any help.

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