This message appears when a CREATE TABLE or ALTER TABLE statement attempts to include the same column in more than one UNIQUE constraint, or in one PRIMARY KEY constraint and one or more UNIQUE constraints, within the same statement. A column may participate in at most one UNIQUE constraint; if a column participates in a UNIQUE constraint, it cannot subsequently participate in a primary key.

This message is also generated when the same column name is repeated in a UNIQUE constraint definition in a CREATE TABLE or ALTER TABLE statement. A particular column name can be included only once in a table constraint definition.