diff --git a/server/models/contests/getAllParticipantsDetails.js b/server/models/contests/getAllParticipantsDetails.js
index a9065ed..f06aa17 100644
--- a/server/models/contests/getAllParticipantsDetails.js
+++ b/server/models/contests/getAllParticipantsDetails.js
@@ -13,9 +13,9 @@ function getAllParticipantsDetails({ username, params }) {
   return new Promise((resolve, reject) => {
     const { contest_id: contestId } = params
     pool.query(
-      `SELECT username, full_name, admission_number, email, mobile, department, course, admission_year, profile_img FROM users 
-      INNER JOIN  contests_participants ON users.username=contests_participants.participant 
-      WHERE EXISTS(SELECT 1 FROM contests_moderators WHERE contest_id=? AND moderator=?) AND contest_id=?`,
+      `SELECT username, full_name, admission_number, email, mobile, department, course, admission_year, profile_img FROM users u
+      INNER JOIN  contests_participants cp ON u.username = cp.participant 
+      WHERE EXISTS(SELECT 1 FROM contests_moderators WHERE contest_id=? AND moderator=?) AND cp.contest_id=?`,
       [contestId, username, contestId],
       (error, results) => {
         if (error || results === undefined) {
diff --git a/server/models/contests/getContest.js b/server/models/contests/getContest.js
index 3e2448b..2d2e97f 100644
--- a/server/models/contests/getContest.js
+++ b/server/models/contests/getContest.js
@@ -12,8 +12,8 @@ function getContest({ username, params }) {
     const { contest_id: contestId } = params
     pool.query(
       `SELECT * FROM contests WHERE id=? 
-      AND (public=1 OR EXISTS(SELECT 1 FROM user_groups WHERE username=? 
-      AND group_id = ANY (SELECT group_id FROM contests_groups WHERE contest_id=?)))`,
+      AND (public=1 OR EXISTS(SELECT 1 FROM contests_groups cg INNER JOIN user_groups ug ON cg.group_id = ug.group_id 
+      WHERE ug.username=? AND cg.contest_id=?))`,
       [contestId, username, contestId],
       (error, results) => {
         if (error || results === undefined) {
diff --git a/server/models/contests/getContests.js b/server/models/contests/getContests.js
index ba688f7..8b93393 100644
--- a/server/models/contests/getContests.js
+++ b/server/models/contests/getContests.js
@@ -13,8 +13,8 @@ function getContests({ username, query }) {
   return new Promise((resolve, reject) => {
     pool.query(
       `SELECT * FROM contests 
-      WHERE  (public=1 OR EXISTS(SELECT 1 FROM user_groups WHERE username=? 
-      AND group_id = ANY (SELECT group_id FROM contests_groups WHERE contest_id=id)))
+      WHERE  (public=1 OR EXISTS(SELECT 1 FROM contests_groups cg INNER JOIN user_groups ug 
+      ON cg.group_id = ug.group_id WHERE ug.username=?))
       ORDER BY end_time`,
       [username],
       (error, results) => {
diff --git a/server/models/contests/getModeratorContests.js b/server/models/contests/getModeratorContests.js
index 0853d83..a61a7b6 100644
--- a/server/models/contests/getModeratorContests.js
+++ b/server/models/contests/getModeratorContests.js
@@ -10,7 +10,7 @@ const { pool } = require('../../models/database')
 function getModeratorContests({ username, query }) {
   return new Promise((resolve, reject) => {
     const limit = Number(query.limit)
-    let sqlQuery = `SELECT * FROM contests WHERE id IN (SELECT contest_id FROM contests_moderators WHERE moderator=?)`
+    let sqlQuery = `SELECT * FROM contests c JOIN contests_moderators cm ON c.id=cm.contest_id WHERE cm.moderator=? `
     let arr = [username]
     if (limit && limit > 0) {
       sqlQuery += ` LIMIT ?`