diff --git a/sql/check.pgsql b/sql/check.pgsql
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+-- Checks that each user has never twice either the same scene or the same recommendation style
+SELECT count(*) = 0
+FROM
+    Experiment as E1,
+    Experiment as E2,
+    CoinCombination as C1,
+    CoinCombination as C2
+
+WHERE
+        E1.user_id = E2.user_id
+    AND E1.id != E2.id
+    AND E1.coin_combination_id = C1.id
+    AND E2.coin_combination_id = C2.id
+    AND (E1.recommendation_style = E2.recommendation_style OR C1.scene_id = C2.scene_id);
+
+-- Checks that a CoinCombination is never used more than 3 times (except for the tutorial)
+SELECT count(*) = 0
+FROM (
+    SELECT count(CoinCombination.id)
+    FROM Experiment, CoinCombination
+    WHERE Experiment.coin_combination_id = CoinCombination.id AND scene_id != 1
+    GROUP BY Experiment.coin_combination_id
+    HAVING count(CoinCombination.id) > 3
+) AS T;
+
+-- Checks that the CoinCombination for a tutorial is only used once
+SELECT count(*) = 0
+FROM (
+    SELECT count(CoinCombination.id)
+    FROM Experiment, CoinCombination
+    WHERE Experiment.coin_combination_id = CoinCombination.id AND scene_id = 1
+    GROUP BY Experiment.coin_combination_id
+    HAVING count(CoinCombination.id) != 1
+) AS T;