diff --git a/solution/1100-1199/1127.User Purchase Platform/README.md b/solution/1100-1199/1127.User Purchase Platform/README.md
index ec564c94da459..26cb5540583b8 100644
--- a/solution/1100-1199/1127.User Purchase Platform/README.md	
+++ b/solution/1100-1199/1127.User Purchase Platform/README.md	
@@ -65,29 +65,29 @@ Result table:
 ```sql
 # Write your MySQL query statement below
 WITH
-    s AS (
+    P AS (
         SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'mobile' FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'both' FROM Spending
     ),
-    t AS (
+    T AS (
         SELECT
             user_id,
             spend_date,
-            if(count(platform) = 2, 'both', platform) AS platform,
-            sum(amount) AS amount
+            sum(amount) AS amount,
+            if(count(platform) = 1, platform, 'both') AS platform
         FROM Spending
         GROUP BY 1, 2
     )
 SELECT
-    t1.*,
+    p.*,
     ifnull(sum(amount), 0) AS total_amount,
-    count(t2.user_id) AS total_users
+    count(t.user_id) AS total_users
 FROM
-    s AS t1
-    LEFT JOIN t AS t2 USING (spend_date, platform)
+    P AS p
+    LEFT JOIN T AS t USING (spend_date, platform)
 GROUP BY 1, 2;
 ```
 
diff --git a/solution/1100-1199/1127.User Purchase Platform/README_EN.md b/solution/1100-1199/1127.User Purchase Platform/README_EN.md
index c225a876d59a1..915af2c8a0b0c 100644
--- a/solution/1100-1199/1127.User Purchase Platform/README_EN.md	
+++ b/solution/1100-1199/1127.User Purchase Platform/README_EN.md	
@@ -69,29 +69,29 @@ On 2019-07-02, user 2 purchased using mobile <strong>only</strong>, user 3 purch
 ```sql
 # Write your MySQL query statement below
 WITH
-    s AS (
+    P AS (
         SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'mobile' FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'both' FROM Spending
     ),
-    t AS (
+    T AS (
         SELECT
             user_id,
             spend_date,
-            if(count(platform) = 2, 'both', platform) AS platform,
-            sum(amount) AS amount
+            sum(amount) AS amount,
+            if(count(platform) = 1, platform, 'both') AS platform
         FROM Spending
         GROUP BY 1, 2
     )
 SELECT
-    t1.*,
+    p.*,
     ifnull(sum(amount), 0) AS total_amount,
-    count(t2.user_id) AS total_users
+    count(t.user_id) AS total_users
 FROM
-    s AS t1
-    LEFT JOIN t AS t2 USING (spend_date, platform)
+    P AS p
+    LEFT JOIN T AS t USING (spend_date, platform)
 GROUP BY 1, 2;
 ```
 
diff --git a/solution/1100-1199/1127.User Purchase Platform/Solution.sql b/solution/1100-1199/1127.User Purchase Platform/Solution.sql
index 540c6f39e1e0d..ce96567abb255 100644
--- a/solution/1100-1199/1127.User Purchase Platform/Solution.sql	
+++ b/solution/1100-1199/1127.User Purchase Platform/Solution.sql	
@@ -1,26 +1,26 @@
 # Write your MySQL query statement below
 WITH
-    s AS (
+    P AS (
         SELECT DISTINCT spend_date, 'desktop' AS platform FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'mobile' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'mobile' FROM Spending
         UNION
-        SELECT DISTINCT spend_date, 'both' AS platform FROM Spending
+        SELECT DISTINCT spend_date, 'both' FROM Spending
     ),
-    t AS (
+    T AS (
         SELECT
             user_id,
             spend_date,
-            if(count(platform) = 2, 'both', platform) AS platform,
-            sum(amount) AS amount
+            sum(amount) AS amount,
+            if(count(platform) = 1, platform, 'both') AS platform
         FROM Spending
         GROUP BY 1, 2
     )
 SELECT
-    t1.*,
+    p.*,
     ifnull(sum(amount), 0) AS total_amount,
-    count(t2.user_id) AS total_users
+    count(t.user_id) AS total_users
 FROM
-    s AS t1
-    LEFT JOIN t AS t2 USING (spend_date, platform)
+    P AS p
+    LEFT JOIN T AS t USING (spend_date, platform)
 GROUP BY 1, 2;
diff --git a/solution/1100-1199/1132.Reported Posts II/README.md b/solution/1100-1199/1132.Reported Posts II/README.md
index 3807f1a04ed3a..ee6685ba74e75 100644
--- a/solution/1100-1199/1132.Reported Posts II/README.md	
+++ b/solution/1100-1199/1132.Reported Posts II/README.md	
@@ -98,18 +98,20 @@ Removals table:
 
 ```sql
 # Write your MySQL query statement below
-SELECT
-    round(avg(avg_per * 100), 2) AS average_daily_percent
-FROM
-    (
+WITH
+    T AS (
         SELECT
-            count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
+            count(DISTINCT t2.post_id) / count(
+                DISTINCT t1.post_id
+            ) * 100 AS percent
         FROM
             Actions AS t1
             LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
-        WHERE t1.extra = 'spam'
+        WHERE extra = 'spam'
         GROUP BY action_date
-    ) AS t3;
+    )
+SELECT round(avg(percent), 2) AS average_daily_percent
+FROM T;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1132.Reported Posts II/README_EN.md b/solution/1100-1199/1132.Reported Posts II/README_EN.md
index 238e4cd9d0da1..0e4754fd2e910 100644
--- a/solution/1100-1199/1132.Reported Posts II/README_EN.md	
+++ b/solution/1100-1199/1132.Reported Posts II/README_EN.md	
@@ -93,18 +93,20 @@ Note that the output is only one number and that we do not care about the remove
 
 ```sql
 # Write your MySQL query statement below
-SELECT
-    round(avg(avg_per * 100), 2) AS average_daily_percent
-FROM
-    (
+WITH
+    T AS (
         SELECT
-            count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
+            count(DISTINCT t2.post_id) / count(
+                DISTINCT t1.post_id
+            ) * 100 AS percent
         FROM
             Actions AS t1
             LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
-        WHERE t1.extra = 'spam'
+        WHERE extra = 'spam'
         GROUP BY action_date
-    ) AS t3;
+    )
+SELECT round(avg(percent), 2) AS average_daily_percent
+FROM T;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1132.Reported Posts II/Solution.sql b/solution/1100-1199/1132.Reported Posts II/Solution.sql
index 90fbf8cf915a9..deccf0c9e7036 100644
--- a/solution/1100-1199/1132.Reported Posts II/Solution.sql	
+++ b/solution/1100-1199/1132.Reported Posts II/Solution.sql	
@@ -1,13 +1,15 @@
 # Write your MySQL query statement below
-SELECT
-    round(avg(avg_per * 100), 2) AS average_daily_percent
-FROM
-    (
+WITH
+    T AS (
         SELECT
-            count(DISTINCT t2.post_id) / count(DISTINCT t1.post_id) AS avg_per
+            count(DISTINCT t2.post_id) / count(
+                DISTINCT t1.post_id
+            ) * 100 AS percent
         FROM
             Actions AS t1
             LEFT JOIN Removals AS t2 ON t1.post_id = t2.post_id
-        WHERE t1.extra = 'spam'
+        WHERE extra = 'spam'
         GROUP BY action_date
-    ) AS t3;
+    )
+SELECT round(avg(percent), 2) AS average_daily_percent
+FROM T;
diff --git a/solution/1100-1199/1141.User Activity for the Past 30 Days I/README.md b/solution/1100-1199/1141.User Activity for the Past 30 Days I/README.md
index dd38e4db0e308..2c56706ed7277 100644
--- a/solution/1100-1199/1141.User Activity for the Past 30 Days I/README.md	
+++ b/solution/1100-1199/1141.User Activity for the Past 30 Days I/README.md	
@@ -66,19 +66,22 @@ Activity table:
 
 <!-- 这里可写通用的实现逻辑 -->
 
+**方法一：GROUP BY + HAVING**
+
+我们查询出所有在 `2019-07-27` 且在 $30$ 天内的所有活动记录，然后按照日期分组，统计每天的去重活跃用户数。
+
 <!-- tabs:start -->
 
 ### **SQL**
 
 ```sql
-SELECT
-    activity_date AS day,
-    COUNT(DISTINCT user_id) AS active_users
+# Write your MySQL query statement below
+SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
 FROM Activity
 WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30
-GROUP BY activity_date;
+    activity_date <= '2019-07-27'
+    AND datediff('2019-07-27', activity_date) < 30
+GROUP BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1141.User Activity for the Past 30 Days I/README_EN.md b/solution/1100-1199/1141.User Activity for the Past 30 Days I/README_EN.md
index ed93062ca63d7..2346e71e095d2 100644
--- a/solution/1100-1199/1141.User Activity for the Past 30 Days I/README_EN.md	
+++ b/solution/1100-1199/1141.User Activity for the Past 30 Days I/README_EN.md	
@@ -67,14 +67,13 @@ Activity table:
 ### **SQL**
 
 ```sql
-SELECT
-    activity_date AS day,
-    COUNT(DISTINCT user_id) AS active_users
+# Write your MySQL query statement below
+SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
 FROM Activity
 WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30
-GROUP BY activity_date;
+    activity_date <= '2019-07-27'
+    AND datediff('2019-07-27', activity_date) < 30
+GROUP BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1141.User Activity for the Past 30 Days I/Solution.sql b/solution/1100-1199/1141.User Activity for the Past 30 Days I/Solution.sql
index 1df9e22b6168d..d2880d36d7d80 100644
--- a/solution/1100-1199/1141.User Activity for the Past 30 Days I/Solution.sql	
+++ b/solution/1100-1199/1141.User Activity for the Past 30 Days I/Solution.sql	
@@ -1,8 +1,7 @@
-SELECT
-    activity_date AS day,
-    COUNT(DISTINCT user_id) AS active_users
+# Write your MySQL query statement below
+SELECT activity_date AS day, count(DISTINCT user_id) AS active_users
 FROM Activity
 WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30
-GROUP BY activity_date;
+    activity_date <= '2019-07-27'
+    AND datediff('2019-07-27', activity_date) < 30
+GROUP BY 1;
diff --git a/solution/1100-1199/1142.User Activity for the Past 30 Days II/README.md b/solution/1100-1199/1142.User Activity for the Past 30 Days II/README.md
index 98d4393241884..acf1cc4d37f7f 100644
--- a/solution/1100-1199/1142.User Activity for the Past 30 Days II/README.md	
+++ b/solution/1100-1199/1142.User Activity for the Past 30 Days II/README.md	
@@ -72,15 +72,18 @@ Activity 表：
 
 ```sql
 # Write your MySQL query statement below
-SELECT
-    IFNULL(
-        ROUND(COUNT(DISTINCT session_id) / COUNT(DISTINCT user_id), 2),
-        0
-    ) AS average_sessions_per_user
-FROM Activity
-WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30;
+WITH
+    T AS (
+        SELECT
+            count(DISTINCT session_id) AS sessions
+        FROM Activity
+        WHERE
+            activity_date <= '2019-07-27'
+            AND datediff('2019-07-27', activity_date) < 30
+        GROUP BY user_id
+    )
+SELECT ifnull(round(avg(sessions), 2), 0) AS average_sessions_per_user
+FROM T;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1142.User Activity for the Past 30 Days II/README_EN.md b/solution/1100-1199/1142.User Activity for the Past 30 Days II/README_EN.md
index bd902626aa2ad..d4e78d5189b52 100644
--- a/solution/1100-1199/1142.User Activity for the Past 30 Days II/README_EN.md	
+++ b/solution/1100-1199/1142.User Activity for the Past 30 Days II/README_EN.md	
@@ -68,15 +68,18 @@ Activity table:
 
 ```sql
 # Write your MySQL query statement below
-SELECT
-    IFNULL(
-        ROUND(COUNT(DISTINCT session_id) / COUNT(DISTINCT user_id), 2),
-        0
-    ) AS average_sessions_per_user
-FROM Activity
-WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30;
+WITH
+    T AS (
+        SELECT
+            count(DISTINCT session_id) AS sessions
+        FROM Activity
+        WHERE
+            activity_date <= '2019-07-27'
+            AND datediff('2019-07-27', activity_date) < 30
+        GROUP BY user_id
+    )
+SELECT ifnull(round(avg(sessions), 2), 0) AS average_sessions_per_user
+FROM T;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1142.User Activity for the Past 30 Days II/Solution.sql b/solution/1100-1199/1142.User Activity for the Past 30 Days II/Solution.sql
index f171d6352d451..14c0ee9338951 100644
--- a/solution/1100-1199/1142.User Activity for the Past 30 Days II/Solution.sql	
+++ b/solution/1100-1199/1142.User Activity for the Past 30 Days II/Solution.sql	
@@ -1,10 +1,13 @@
 # Write your MySQL query statement below
-SELECT
-    IFNULL(
-        ROUND(COUNT(DISTINCT session_id) / COUNT(DISTINCT user_id), 2),
-        0
-    ) AS average_sessions_per_user
-FROM Activity
-WHERE
-    DATEDIFF('2019-07-27', activity_date) >= 0
-    AND DATEDIFF('2019-07-27', activity_date) < 30;
+WITH
+    T AS (
+        SELECT
+            count(DISTINCT session_id) AS sessions
+        FROM Activity
+        WHERE
+            activity_date <= '2019-07-27'
+            AND datediff('2019-07-27', activity_date) < 30
+        GROUP BY user_id
+    )
+SELECT ifnull(round(avg(sessions), 2), 0) AS average_sessions_per_user
+FROM T;
diff --git a/solution/1100-1199/1148.Article Views I/README.md b/solution/1100-1199/1148.Article Views I/README.md
index 2c5cead168379..d8db86a2076af 100644
--- a/solution/1100-1199/1148.Article Views I/README.md	
+++ b/solution/1100-1199/1148.Article Views I/README.md	
@@ -55,17 +55,20 @@ Views 表：
 
 <!-- 这里可写通用的实现逻辑 -->
 
-“`DISTINCT` + `ORDER BY`” 实现。
+**方法一：DISTINCT + WHERE**
+
+我们利用 `WHERE` 子句来筛选出 `author_id` 和 `viewer_id` 相等的记录，然后利用 `DISTINCT` 来去重，最后按照 `id` 排序即可。
 
 <!-- tabs:start -->
 
 ### **SQL**
 
 ```sql
-SELECT DISTINCT (author_id) AS id
+# Write your MySQL query statement below
+SELECT DISTINCT author_id AS id
 FROM Views
 WHERE author_id = viewer_id
-ORDER BY id;
+ORDER BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1148.Article Views I/README_EN.md b/solution/1100-1199/1148.Article Views I/README_EN.md
index 89898a3bf15d1..147033c783f5e 100644
--- a/solution/1100-1199/1148.Article Views I/README_EN.md	
+++ b/solution/1100-1199/1148.Article Views I/README_EN.md	
@@ -61,10 +61,11 @@ Views table:
 ### **SQL**
 
 ```sql
-SELECT DISTINCT (author_id) AS id
+# Write your MySQL query statement below
+SELECT DISTINCT author_id AS id
 FROM Views
 WHERE author_id = viewer_id
-ORDER BY id;
+ORDER BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1148.Article Views I/Solution.sql b/solution/1100-1199/1148.Article Views I/Solution.sql
index 6c4c149059fe3..2a3cd6c02366a 100644
--- a/solution/1100-1199/1148.Article Views I/Solution.sql	
+++ b/solution/1100-1199/1148.Article Views I/Solution.sql	
@@ -1,4 +1,5 @@
-SELECT DISTINCT (author_id) AS id
+# Write your MySQL query statement below
+SELECT DISTINCT author_id AS id
 FROM Views
 WHERE author_id = viewer_id
-ORDER BY id;
+ORDER BY 1;
diff --git a/solution/1100-1199/1149.Article Views II/README.md b/solution/1100-1199/1149.Article Views II/README.md
index c9c6b74de1f6b..2390d8b57f362 100644
--- a/solution/1100-1199/1149.Article Views II/README.md	
+++ b/solution/1100-1199/1149.Article Views II/README.md	
@@ -61,7 +61,9 @@ Views 表:
 
 <!-- 这里可写通用的实现逻辑 -->
 
-“`DISTINCT` + `GROUP BY`” 实现。
+**方法一：DISTINCT + GROUP BY + HAVING**
+
+我们将数据按照 `viewer_id` 和 `view_date` 分组，然后利用 `HAVING` 子句来筛选出浏览文章数大于 $1$ 的记录，最后按照 `id` 去重排序即可。
 
 <!-- tabs:start -->
 
@@ -69,12 +71,11 @@ Views 表:
 
 ```sql
 # Write your MySQL query statement below
-SELECT DISTINCT
-    (viewer_id) AS id
+SELECT DISTINCT viewer_id AS id
 FROM Views
-GROUP BY view_date, viewer_id
-HAVING COUNT(DISTINCT article_id) > 1
-ORDER BY id;
+GROUP BY viewer_id, view_date
+HAVING count(DISTINCT article_id) > 1
+ORDER BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1149.Article Views II/README_EN.md b/solution/1100-1199/1149.Article Views II/README_EN.md
index 368ea900e6f1d..382c2ab9fbc47 100644
--- a/solution/1100-1199/1149.Article Views II/README_EN.md	
+++ b/solution/1100-1199/1149.Article Views II/README_EN.md	
@@ -62,12 +62,11 @@ Views table:
 
 ```sql
 # Write your MySQL query statement below
-SELECT DISTINCT
-    (viewer_id) AS id
+SELECT DISTINCT viewer_id AS id
 FROM Views
-GROUP BY view_date, viewer_id
-HAVING COUNT(DISTINCT article_id) > 1
-ORDER BY id;
+GROUP BY viewer_id, view_date
+HAVING count(DISTINCT article_id) > 1
+ORDER BY 1;
 ```
 
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1149.Article Views II/Solution.sql b/solution/1100-1199/1149.Article Views II/Solution.sql
index 6a3c820a27bbe..55402d92887bc 100644
--- a/solution/1100-1199/1149.Article Views II/Solution.sql	
+++ b/solution/1100-1199/1149.Article Views II/Solution.sql	
@@ -1,7 +1,6 @@
 # Write your MySQL query statement below
-SELECT DISTINCT
-    (viewer_id) AS id
+SELECT DISTINCT viewer_id AS id
 FROM Views
-GROUP BY view_date, viewer_id
-HAVING COUNT(DISTINCT article_id) > 1
-ORDER BY id;
+GROUP BY viewer_id, view_date
+HAVING count(DISTINCT article_id) > 1
+ORDER BY 1;
diff --git a/solution/1100-1199/1158.Market Analysis I/README.md b/solution/1100-1199/1158.Market Analysis I/README.md
index 80f168bcd0802..68d33fa1a27ef 100644
--- a/solution/1100-1199/1158.Market Analysis I/README.md	
+++ b/solution/1100-1199/1158.Market Analysis I/README.md	
@@ -125,4 +125,16 @@ FROM
 GROUP BY user_id;
 ```
 
+```sql
+# Write your MySQL query statement below
+SELECT
+    user_id AS buyer_id,
+    join_date,
+    ifnull(sum(year(order_date) = 2019), 0) AS orders_in_2019
+FROM
+    Users AS u
+    LEFT JOIN Orders AS o ON u.user_id = buyer_id
+GROUP BY 1;
+```
+
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1158.Market Analysis I/README_EN.md b/solution/1100-1199/1158.Market Analysis I/README_EN.md
index 5b17a9f80d1a1..67b394b4a1c04 100644
--- a/solution/1100-1199/1158.Market Analysis I/README_EN.md	
+++ b/solution/1100-1199/1158.Market Analysis I/README_EN.md	
@@ -122,4 +122,16 @@ FROM
 GROUP BY user_id;
 ```
 
+```sql
+# Write your MySQL query statement below
+SELECT
+    user_id AS buyer_id,
+    join_date,
+    ifnull(sum(year(order_date) = 2019), 0) AS orders_in_2019
+FROM
+    Users AS u
+    LEFT JOIN Orders AS o ON u.user_id = buyer_id
+GROUP BY 1;
+```
+
 <!-- tabs:end -->
diff --git a/solution/1100-1199/1158.Market Analysis I/Solution.sql b/solution/1100-1199/1158.Market Analysis I/Solution.sql
index 88358aea0c455..c350404e187e9 100644
--- a/solution/1100-1199/1158.Market Analysis I/Solution.sql	
+++ b/solution/1100-1199/1158.Market Analysis I/Solution.sql	
@@ -1,9 +1,9 @@
 # Write your MySQL query statement below
 SELECT
-    u.user_id AS buyer_id,
-    u.join_date,
-    count(order_id) AS orders_in_2019
+    user_id AS buyer_id,
+    join_date,
+    ifnull(sum(year(order_date) = 2019), 0) AS orders_in_2019
 FROM
     Users AS u
-    LEFT JOIN Orders AS o ON u.user_id = o.buyer_id AND YEAR(order_date) = 2019
-GROUP BY user_id;
+    LEFT JOIN Orders AS o ON u.user_id = buyer_id
+GROUP BY 1;