feat(backend) update (unfinished)

backend/server/src/modules/blog/schema.sql

@@ -0,0 +1,41 @@
+CREATE TABLE tags
+(
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(20) UNIQUE NOT NULL,
+    description TEXT
+);
+
+CREATE TABLE categories
+(
+    id          SERIAL PRIMARY KEY,
+    name        VARCHAR(20) UNIQUE NOT NULL,
+    description TEXT
+);
+
+CREATE TABLE posts
+(
+    id             SERIAL PRIMARY KEY,
+    identifier     VARCHAR(50) UNIQUE                NOT NULL,
+    title          VARCHAR(255)                      NOT NULL,
+    subtitle       VARCHAR(255)                      NOT NULL,
+    published_date DATE                              NOT NULL,
+    last_update    DATE,
+    content        TEXT                              NOT NULL,
+
+    category       SERIAL REFERENCES categories (id) NOT NULL
+);
+
+CREATE TABLE post_tag
+(
+    post SERIAL REFERENCES posts (id),
+    tag  SERIAL REFERENCES tags (id)
+);
+
+CREATE TABLE metadata
+(
+    pid        SERIAL REFERENCES posts (id) NOT NULL,
+    meta_key   VARCHAR(50)                  NOT NULL,
+    meta_value TEXT                         NOT NULL,
+
+    CONSTRAINT meta_pk PRIMARY KEY (pid, meta_key)
+);