schema: add unique constraint on access_key

schema/ttrss_schema_mysql.sql

@@ -432,7 +432,7 @@ create table ttrss_linked_instances (id integer not null primary key auto_increm
 	last_connected datetime not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null) TYPE=InnoDB DEFAULT CHARSET=UTF8;
 
 create table ttrss_linked_feeds (

schema/ttrss_schema_pgsql.sql

@@ -392,7 +392,7 @@ create table ttrss_linked_instances (id serial not null primary key,
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null);
 
 create table ttrss_linked_feeds (

schema/versions/mysql/84.sql

@@ -4,7 +4,7 @@ create table ttrss_linked_instances (id integer not null primary key auto_increm
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null) TYPE=InnoDB DEFAULT CHARSET=UTF8;
 
 create table ttrss_linked_feeds (

schema/versions/pgsql/84.sql

@@ -4,7 +4,7 @@ create table ttrss_linked_instances (id serial not null primary key,
 	last_connected timestamp not null,
 	last_status_in integer not null,
 	last_status_out integer not null,
-	access_key varchar(250) not null,
+	access_key varchar(250) not null unique,
 	access_url text not null);
 
 create table ttrss_linked_feeds (