diff --git a/Persistence.md b/Persistence.md
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--- a/Persistence.md
+++ b/Persistence.md
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-## Persistence will be added once database and back-end is finished
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+All data is stored in the MySQL-database. User sessions are stored in server memory. 
+
+#### ER-Diagram
+
+![entityRelationshipDiagram](uploads/c1ff984303b489fdbff06b26705af2a0/entityRelationshipDiagram.png)
+
+
+##### The SQL calls to create the database tables needed:
+
+```sql
+-- WARNING: Will delete EVERYTHING in the database!
+
+DROP TABLE IF EXISTS matches;
+DROP TABLE IF EXISTS teams;
+DROP TABLE IF EXISTS tournaments;
+DROP TABLE IF EXISTS users;
+
+-- Create the tables
+CREATE TABLE tournaments (
+    id INTEGER PRIMARY KEY AUTO_INCREMENT,
+    name TEXT NOT NULL,
+    description TEXT,
+    prize TEXT,
+    teamLimit INTEGER NOT NULL,
+    startTime DATETIME NOT NULL,
+    endTime DATETIME NOT NULL
+);
+
+CREATE TABLE teams (
+    id INTEGER PRIMARY KEY AUTO_INCREMENT,
+    tournamentId INTEGER NOT NULL,
+    name TEXT NOT NULL,
+
+    FOREIGN KEY (tournamentId) REFERENCES tournaments (id) ON DELETE CASCADE
+);
+
+CREATE TABLE matches (
+    id INTEGER PRIMARY KEY AUTO_INCREMENT,
+    tournamentId INTEGER NOT NULL,
+    parentMatchId INTEGER,
+    team1Id INTEGER,
+    team2Id INTEGER,
+    winnerId INTEGER,
+    tier INTEGER,
+
+    FOREIGN KEY (tournamentId) REFERENCES tournaments (id) ON DELETE CASCADE,
+    FOREIGN KEY (team1Id) REFERENCES teams (id) ON DELETE SET NULL,
+    FOREIGN KEY (team2Id) REFERENCES teams (id) ON DELETE SET NULL,
+    FOREIGN KEY (winnerId) REFERENCES teams (id) ON DELETE SET NULL
+);
+
+CREATE TABLE users (
+    id INTEGER PRIMARY KEY AUTO_INCREMENT,
+    googleId TEXT,
+    name TEXT,
+    email TEXT NOT NULL,
+    isManager BOOLEAN NOT NULL
+);
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