diff --git a/migrations/20210623000000_reminder_message_embed.sql b/migrations/20210623000000_reminder_message_embed.sql
index 3293f36..e6b83cb 100644
--- a/migrations/20210623000000_reminder_message_embed.sql
+++ b/migrations/20210623000000_reminder_message_embed.sql
@@ -46,7 +46,7 @@ CREATE TABLE reminders_new (
     PRIMARY KEY (id),
 
     FOREIGN KEY (`channel_id`) REFERENCES channels (`id`) ON DELETE CASCADE,
-    CONSTRAINT `reminders_ibfk_2` FOREIGN KEY (`set_by`) REFERENCES `users` (`id`) ON DELETE SET NULL
+    FOREIGN KEY (`set_by`) REFERENCES users (`id`) ON DELETE SET NULL
 
     # disallow having a reminder as restartable if it has no interval
     -- , CONSTRAINT restartable_interval_mutex CHECK (`restartable` = 0 OR `interval` IS NULL)
diff --git a/migrations/20240630150936_dashboard_preferences.sql b/migrations/20240630150936_dashboard_preferences.sql
index d4f2f56..94f7649 100644
--- a/migrations/20240630150936_dashboard_preferences.sql
+++ b/migrations/20240630150936_dashboard_preferences.sql
@@ -1,27 +1,87 @@
-SET FOREIGN_KEY_CHECKS=0;
+SET FOREIGN_KEY_CHECKS = 0;
 
 -- Tables no longer needed as old dashboard is decomm.
-DROP TABLE guild_users;
-DROP TABLE events;
+DROP TABLE IF EXISTS guild_users;
+DROP TABLE IF EXISTS events;
 
-ALTER TABLE users ADD COLUMN `reset_inputs_on_create` BOOLEAN NOT NULL DEFAULT 0;
-ALTER TABLE users ADD COLUMN `use_browser_timezone` BOOLEAN NOT NULL DEFAULT 1;
-ALTER TABLE users ADD COLUMN `dashboard_color_scheme` ENUM('system', 'light', 'dark') NOT NULL DEFAULT 'system';
+CREATE TABLE users_new
+(
+    id                     BIGINT UNSIGNED,
+    dm_channel             INT UNSIGNED UNIQUE              NOT NULL,
+    timezone               VARCHAR(32)                      NOT NULL DEFAULT 'UTC',
+    meridian_time          BOOLEAN                          NOT NULL DEFAULT 0,
+    allowed_dm             BOOLEAN                          NOT NULL DEFAULT 1,
+    reset_inputs_on_create BOOLEAN                          NOT NULL DEFAULT 0,
+    use_browser_timezone   BOOLEAN                          NOT NULL DEFAULT 1,
+    dashboard_color_scheme ENUM ('system', 'light', 'dark') NOT NULL DEFAULT 'system',
 
-ALTER TABLE users DROP COLUMN `language`;
-ALTER TABLE users DROP COLUMN `patreon`;
-ALTER TABLE users DROP COLUMN `name`;
+    PRIMARY KEY (id),
+    FOREIGN KEY `fk_user_dm_channel` (dm_channel) REFERENCES channels (id) ON DELETE RESTRICT,
+    -- Useful for bot startup times
+    INDEX `index_timezone` (timezone)
+);
 
-ALTER TABLE todos DROP CONSTRAINT todos_ibfk_5, MODIFY COLUMN user_id BIGINT UNSIGNED;
-UPDATE todos SET user_id = (SELECT user FROM users WHERE id = user_id);
-ALTER TABLE todos ADD CONSTRAINT todos_user_fk FOREIGN KEY (user_id) REFERENCES users(user);
+-- Drop some dodgy user entries
+CREATE TEMPORARY TABLE dupe_users
+SELECT dm_channel
+FROM users u1
+WHERE (SELECT COUNT(1) FROM users u2 WHERE u2.dm_channel = u1.dm_channel) > 1;
 
-ALTER TABLE reminders DROP CONSTRAINT reminders_ibfk_2, MODIFY COLUMN set_by BIGINT UNSIGNED;
-UPDATE reminders SET set_by = (SELECT user FROM users WHERE id = set_by);
-ALTER TABLE reminders ADD CONSTRAINT reminder_user_fk FOREIGN KEY (set_by) REFERENCES users(user);
+DELETE
+FROM users
+WHERE dm_channel IN (SELECT * FROM dupe_users);
 
-ALTER TABLE users DROP PRIMARY KEY, CHANGE id id INT UNSIGNED, ADD PRIMARY KEY (`user`);
-ALTER TABLE users DROP COLUMN `id`;
-ALTER TABLE users RENAME COLUMN `user` TO `id`;
+INSERT INTO users_new (id, dm_channel, timezone, meridian_time, allowed_dm)
+SELECT `user`, dm_channel, IFNULL(timezone, 'UTC'), meridian_time, allowed_dm
+FROM users;
 
-SET FOREIGN_KEY_CHECKS=1;
+-- Add new user ID column
+ALTER TABLE todos
+    ADD COLUMN user_id_new BIGINT UNSIGNED;
+-- Reference new table with new column
+ALTER TABLE todos
+    ADD CONSTRAINT `todos_user_fk` FOREIGN KEY (user_id_new) REFERENCES users_new (id) ON DELETE SET NULL ON UPDATE CASCADE;
+-- Populate new column
+UPDATE todos
+SET user_id_new = (SELECT user FROM users WHERE id = user_id);
+-- Prepare a statement to drop the old constraint
+SELECT @todo_query := CONCAT('ALTER TABLE todos DROP FOREIGN KEY ', constraint_name)
+FROM information_schema.key_column_usage
+WHERE constraint_schema = DATABASE()
+  AND table_name = 'todos'
+  AND column_name = 'user_id';
+PREPARE todo_stmt FROM @todo_query;
+EXECUTE todo_stmt;
+-- Drop old column
+ALTER TABLE todos
+    DROP COLUMN user_id;
+-- Rename new column
+ALTER TABLE todos RENAME COLUMN user_id_new TO user_id;
+
+-- Add new set by column
+ALTER TABLE reminders
+    ADD COLUMN set_by_new BIGINT UNSIGNED;
+-- Reference new table with new column
+ALTER TABLE reminders
+    ADD CONSTRAINT `reminders_set_by_fk` FOREIGN KEY (set_by_new) REFERENCES users_new (id) ON DELETE SET NULL ON UPDATE CASCADE;
+-- Populate new column
+UPDATE reminders
+SET set_by_new = (SELECT user FROM users WHERE id = set_by);
+-- Prepare a statement to drop the old constraint
+SELECT @reminders_query := CONCAT('ALTER TABLE reminders DROP FOREIGN KEY ', constraint_name)
+FROM information_schema.key_column_usage
+WHERE constraint_schema = DATABASE()
+  AND table_name = 'reminders'
+  AND column_name = 'set_by';
+PREPARE reminders_stmt FROM @reminders_query;
+EXECUTE reminders_stmt;
+-- Drop old column
+ALTER TABLE reminders
+    DROP COLUMN set_by;
+ALTER TABLE reminders RENAME COLUMN set_by_new TO set_by;
+
+-- Swap the tables
+DROP TABLE users;
+RENAME TABLE users_new TO users;
+
+SET FOREIGN_KEY_CHECKS = 1;