If my users tables is

CREATE TABLE users ( user_id SERIAL PRIMARY KEY, -- add first, middle, and last name first_name VARCHAR(50) NULL DEFAULT NULL, middle_name VARCHAR(50) NULL DEFAULT NULL, last_name VARCHAR(50) NULL DEFAULT NULL, -- mobile phone used for login purpose mobile VARCHAR(20) UNIQUE NOT NULL, password VARCHAR(255) NOT NULL, email VARCHAR(100) UNIQUE NOT NULL, -- a short intro about the user intro VARCHAR(255) NULL DEFAULT NULL, last_login DATETIME NULL DEFAULT NULL, registered_at TIMESTAMP DEFAULT NOW() );

And posts is as,

```psql
CREATE TABLE posts (
post_id SERIAL PRIMARY KEY,
user_id INTEGER NOT NULL,
title VARCHAR(255) NOT NULL,
content TEXT NOT NULL,
created_at TIMESTAMP DEFAULT NOW(),
published_at TIMESTAMP
);

There is a post bout Guide To Design Database For Blog Management In MySQL@https://mysql.tutorials24x7.com/blog/guide-to-design-a-database-for-blog-management-in-mysql を知っていますか。　what is the purpose of dedign posts ans psot_meta as

CREATE TABLE `blog`.`post` (
  `id` BIGINT NOT NULL AUTO_INCREMENT,
  `authorId` BIGINT NOT NULL,
  `parentId` BIGINT NULL DEFAULT NULL,
  `title` VARCHAR(75) NOT NULL,
  `metaTitle` VARCHAR(100) NULL,
  `slug` VARCHAR(100) NOT NULL,
  `summary` TINYTEXT NULL,
  `published` TINYINT(1) NOT NULL DEFAULT 0,
  `createdAt` DATETIME NOT NULL,
  `updatedAt` DATETIME NULL DEFAULT NULL,
  `publishedAt` DATETIME NULL DEFAULT NULL,
  `content` TEXT NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE INDEX `uq_slug` (`slug` ASC),
  INDEX `idx_post_user` (`authorId` ASC),
  CONSTRAINT `fk_post_user`
    FOREIGN KEY (`authorId`)
    REFERENCES `blog`.`user` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION);

ALTER TABLE `blog`.`post` 
ADD INDEX `idx_post_parent` (`parentId` ASC);
ALTER TABLE `blog`.`post` 
ADD CONSTRAINT `fk_post_parent`
  FOREIGN KEY (`parentId`)
  REFERENCES `blog`.`post` (`id`)
  ON DELETE NO ACTION
  ON UPDATE NO ACTION;

and

CREATE TABLE `blog`.`post_meta` (
  `id` BIGINT NOT NULL AUTO_INCREMENT,
  `postId` BIGINT NOT NULL,
  `key` VARCHAR(50) NOT NULL,
  `content` TEXT NULL DEFAULT NULL,
  PRIMARY KEY (`id`),
  INDEX `idx_meta_post` (`postId` ASC),
  UNIQUE INDEX `uq_post_meta` (`postId` ASC, `key` ASC),
  CONSTRAINT `fk_meta_post`
    FOREIGN KEY (`postId`)
    REFERENCES `blog`.`post` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;