add question stat query

dal/db_query/queries.sql

@@ -478,3 +478,86 @@ FROM
     ResultStats rs ON tb.time_interval = rs.time_interval
         LEFT JOIN
     AvTimeStats at ON tb.time_interval = at.time_interval;
+
+-- name: QuestionsStatistics :many
+WITH Funnel AS (
+    SELECT
+        COUNT(DISTINCT session) FILTER (WHERE a.start = FALSE) AS count_start_false,
+        COUNT(DISTINCT session) FILTER (WHERE a.start = TRUE) AS count_start_true,
+        COUNT(DISTINCT CASE WHEN a.result = FALSE AND qid_true_result IS NOT NULL THEN session END) AS count_f_result_with_t_question,
+        COUNT(DISTINCT CASE WHEN a.start = TRUE AND qid_true_result IS NULL THEN session END) AS count_t_start_with_t_question,
+        COUNT(DISTINCT session) FILTER (WHERE a.result = TRUE) AS count_t_result
+    FROM
+        answer a
+            LEFT JOIN (
+            SELECT DISTINCT a.session, q.id AS qid_true_result
+            FROM answer a
+                     JOIN question q ON a.question_id = q.id
+            WHERE a.result = TRUE
+        ) AS q ON a.session = q.session
+    WHERE
+        a.quiz_id = $1
+      AND a.created_at >= TO_TIMESTAMP($2)
+      AND a.created_at <= TO_TIMESTAMP($3)
+),
+     Results AS (
+         SELECT
+             q.title AS question_title,
+             COUNT(*)::FLOAT / NULLIF(SUM(COUNT(*)) FILTER (WHERE a.result = TRUE), 0) AS percentage
+         FROM
+             answer a
+                 JOIN
+             question q ON a.question_id = q.id
+         WHERE
+             a.quiz_id = $1
+           AND a.created_at >= TO_TIMESTAMP($2)
+           AND a.created_at <= TO_TIMESTAMP($3)
+           AND a.result = TRUE
+         GROUP BY
+             q.id, q.title
+         HAVING
+             COUNT(*) >= 1
+     ),
+     Questions AS (
+         SELECT
+             q.title AS question_title,
+             a.content AS answer_content,
+             COUNT(*)::FLOAT / NULLIF(q.total_answers, 0) AS percentage
+         FROM
+             answer a
+                 JOIN (
+                 SELECT q.id, COUNT(*) AS total_answers
+                 FROM question q
+                          JOIN answer a ON q.id = a.question_id
+                 WHERE a.quiz_id = $1
+                   AND a.created_at >= TO_TIMESTAMP($2)
+                   AND a.created_at <= TO_TIMESTAMP($3)
+                 GROUP BY q.id
+             ) q ON a.question_id = q.id
+         WHERE
+             a.quiz_id = $1
+           AND a.created_at >= TO_TIMESTAMP($2)
+           AND a.created_at <= TO_TIMESTAMP($3)
+         GROUP BY
+             q.id, q.title, a.content
+         HAVING
+             COUNT(*) >= 1
+     )
+SELECT
+    Funnel.count_start_false,
+    Funnel.count_start_true,
+    Funnel.count_f_result_with_t_question,
+    Funnel.count_t_start_with_t_question,
+    Funnel.count_t_result,
+    Funnel.count_start_true,
+    Results.question_title AS results_question_title,
+    Results.percentage AS results_percentage,
+    Questions.question_title AS questions_question_title,
+    Questions.answer_content AS questions_answer_content,
+    Questions.percentage AS questions_percentage
+FROM
+    Funnel,
+    Results,
+    Questions;
+
+