added IF NOT EXISTS to create and CRUD for each table

backend/database/sql/schemas/artist_credit.sql

@@ -1,4 +1,4 @@
-CREATE TABLE artist_credit (
+CREATE TABLE IF NOT EXISTS artist_credit (
   id   int PRIMARY KEY,
   text string NOT NULL
 );

backend/database/sql/schemas/artist_credit_artist.sql

@@ -1,4 +1,4 @@
-CREATE TABLE artist_credit_artist (
+CREATE TABLE IF NOT EXISTS artist_credit_artist (
   id   int PRIMARY KEY,
   FOREIGN KEY(artist_id) REFERENCES artists(id),
   FOREIGN KEY(credit_id) REFERENCES artist_credit(id)

backend/database/sql/schemas/artists.sql

@@ -1,4 +1,4 @@
-CREATE TABLE artists (
+CREATE TABLE IF NOT EXISTS artists (
   id   int PRIMARY KEY,
   name text    NOT NULL
 );

backend/database/sql/schemas/audio_files.sql

@@ -1,4 +1,4 @@
-CREATE TABLE audio_files (
+CREATE TABLE IF NOT EXISTS audio_files (
   id int PRIMARY KEY,
   file_path text NOT NULL UNIQUE,
   length_milliseconds int NOT NULL,

backend/database/sql/schemas/cover_art.sql

@@ -1,4 +1,4 @@
-CREATE TABLE cover_art (
+CREATE TABLE IF NOT EXISTS cover_art (
   id   int PRIMARY KEY,
   is_embedded bool NOT NULL DEFAULT(false),
   file_path text NOT NULL,

backend/database/sql/schemas/file_types.sql

@@ -1,4 +1,4 @@
-CREATE TABLE file_types (
+CREATE TABLE IF NOT EXISTS file_types (
   id   INTEGER PRIMARY KEY,
   extension text    NOT NULL UNIQUE
 );

backend/database/sql/schemas/recordings.sql

@@ -1,4 +1,4 @@
-CREATE TABLE recordings (
+CREATE TABLE IF NOT EXISTS recordings (
   id   int PRIMARY KEY,
   name text    NOT NULL,
   FOREIGN KEY(artist_credit_id) REFERENCES artist_credit(id)

backend/database/sql/schemas/release_group_recordings.sql

@@ -1,4 +1,4 @@
-CREATE TABLE release_group_recordings (
+CREATE TABLE IF NOT EXISTS release_group_recordings (
   id   int PRIMARY KEY,
   FOREIGN KEY(release_group_id) REFERENCES release_groups(id),
   FOREIGN KEY(recording_id) REFERENCES recordings(id)

backend/database/sql/schemas/release_groups.sql

@@ -1,4 +1,4 @@
-CREATE TABLE release_groups (
+CREATE TABLE IF NOT EXISTS release_groups (
   id   int PRIMARY KEY,
   name text    NOT NULL,
   FOREIGN KEY(cover_art_id) REFERENCES cover_art(id)