create_unique_constraint

create_unique_constraint(constraint_name: Optional[str], table_name: str, columns: Sequence[str], schema: Optional[str] = None, **kw) → Any

Issue a “create unique constraint” instruction using the current migration context.

e.g.:

from alembic import op

op.create_unique_constraint("uq_user_name", "user", ["name"])

This internally generates a Table object containing the necessary columns, then generates a new UniqueConstraint object which it then associates with the Table. Any event listeners associated with this action will be fired off normally. The AddConstraint construct is ultimately used to generate the ALTER statement.

Parameters:

• name – Name of the unique constraint. The name is necessary so that an ALTER statement can be emitted. For setups that use an automated naming scheme such as that described at Configuring Constraint Naming Conventions, name here can be None, as the event listener will apply the name to the constraint object when it is associated with the table.
• table_name – String name of the source table.
• columns – a list of string column names in the source table.
• deferrable – optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when issuing DDL for this constraint.
• initially – optional string. If set, emit INITIALLY when issuing DDL for this constraint.
• schema – Optional schema name to operate within. To control quoting of the schema outside of the default behavior, use the SQLAlchemy construct quoted_name.