如何为所呈现实体的 H2 编写架构 sql？

Question

我想运行使用 H2 的内部数据库。我有一条新闻附有评论。如果数据库是在 PostgreSQL 中自动创建的，这一切都有效。

我的实体：

public class Comment {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private long id;
    @Column(name = "date")
    private Date date;
    @Column(name = "text")
    private String text;
    @Column(name = "username")
    private String username;
    @Column(name = "id_news")
    private long id_news;

}

public class News {

   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   @Column(name = "id")
   private long id;
   @Column(name = "date")
   private Date date;
   @Column(name = "title")
   private String title;
   @Column(name = "text")
   private String text;
   @OneToMany(cascade = CascadeType.ALL, targetEntity = Comment.class)
   @JoinColumn(name = "id_news")
   private List<Comment> comments;

}

我试图从 postgresql 获取 sql 代码，但它给出了一个错误

CREATE TABLE public.news
(
    id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 9223372036854775807 CACHE 1 ),
    date timestamp without time zone,
    text character varying(255) COLLATE pg_catalog."default",
    title character varying(255) COLLATE pg_catalog."default",
    CONSTRAINT news_pkey PRIMARY KEY (id)
);

CREATE TABLE public.comment
(
    id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 9223372036854775807 CACHE 1 ),
    date timestamp without time zone,
    id_news bigint,
    text character varying(255) COLLATE pg_catalog."default",
    username character varying(255) COLLATE pg_catalog."default",
    CONSTRAINT comment_pkey PRIMARY KEY (id),
    CONSTRAINT fkbptqmm7bn3alb6htitgfrlt95 FOREIGN KEY (id_news)
        REFERENCES public.news (id) MATCH SIMPLE
        ON UPDATE NO ACTION
        ON DELETE NO ACTION
)

我收到这个错误

Syntax error in SQL statement "CREATE TABLE PUBLIC.NEWS ( ID BIGINT NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 9223372036854775807 CACHE 1 ), DATE TIMESTAMP WITHOUT TIME ZONE, TEXT CHARACTER VARYING(255) COLLATE[*] PG_CATALOG.""default"", TITLE CHARACTER VARYING(255) COLLATE PG_CATALOG.""default"", CONSTRAINT NEWS_PKEY PRIMARY KEY (ID) )"; expected "FOR, UNSIGNED, INVISIBLE, VISIBLE, NOT, NULL, AS, DEFAULT, GENERATED, ON, NOT, NULL, AUTO_INCREMENT, BIGSERIAL, SERIAL, IDENTITY, NULL_TO_DEFAULT, SEQUENCE, SELECTIVITY, COMMENT, CONSTRAINT, PRIMARY, UNIQUE, NOT, NULL, COMMENT, CHECK, REFERENCES, ,, )"; SQL statement:
CREATE TABLE public.news ( id bigint NOT NULL GENERATED BY DEFAULT AS IDENTITY ( INCREMENT 1 START 1 MINVALUE 1 MAXVALUE 9223372036854775807 CACHE 1 ), date timestamp without time zone, text character varying(255) COLLATE pg_catalog."default", title character varying(255) COLLATE pg_catalog."default", CONSTRAINT news_pkey PRIMARY KEY (id) ) [42001-200]

我有 Postgresql 方言，

Answer 1

关系数据库支持一般的 SQL 语句，但它们还为其添加了额外的扩展。您在 PostgreSQL 中看到的扩展在 H2 中不起作用。

话虽如此，您的 DDL 将在 H2 中进行少量修改。例如：

create table news (
    id bigint not null generated by default as identity,
    date timestamp without time zone,
    text character varying(255),
    title character varying(255),
    constraint news_pkey primary key (id)
);

create table comment (
    id bigint not null generated by default as identity,
    date timestamp without time zone,
    id_news bigint,
    text character varying(255),
    username character varying(255),
    constraint comment_pkey primary key (id),
    constraint fkbptqmm7bn3alb6htitgfrlt95 foreign key (id_news)
        references news (id)
        on update no action
        on delete no action
);

Answer 2

尝试以下任一步骤

1.Some H2 的语法不同。您可以相应地修改现有的创建查询或在 PostgreSQL 兼容模式 中尝试运行给定 here

2.Enable 在属性中创建并启用 SQL 查询以在应用程序启动时在日志中打印。它将打印创建查询。

spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=create

如何为所呈现实体的 H2 编写架构 sql？

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spring-data-jpa

spring-boot