在 postgresql 中，如何使 "name" 只有在 "deleted" 为 false 时才唯一？

Question

我有以下 table

CREATE TABLE "prm_project_service_product_and_services" (
  "id" BIGSERIAL NOT NULL,
  "name" VARCHAR(60) NOT NULL,
  "note" VARCHAR(256) NOT NULL,
  "version" BIGINT DEFAULT NULL,
  "created_date" TIMESTAMP DEFAULT NULL,
  "created_by_id" BIGINT DEFAULT NULL,
  "last_modified_date" TIMESTAMP DEFAULT NULL,
  "last_modified_by_id" BIGINT DEFAULT NULL,
  "deleted" BOOLEAN NOT NULL DEFAULT FALSE,
  PRIMARY KEY ("id"),
  CONSTRAINT project_service_product_and_services_unique UNIQUE ("name")
);

我只想在 deleted 为 false 时使 name 唯一，这可能吗？

Answer 1

您可以使用部分唯一索引：

create unique index punq_prm_project_service_product_and_services
    on prm_project_service_product_and_services(name)
    where not deleted;

如 documentation 中所述，这必须使用索引而不是唯一约束来完成：

A uniqueness restriction covering only some rows cannot be written as a unique constraint, but it is possible to enforce such a restriction by creating a unique partial index.

在 postgresql 中，如何使 "name" 只有在 "deleted" 为 false 时才唯一？

In postgresql, how can I make "name" unique only when "deleted" is false?

sql

postgresql

postgresql-9.5