Add docs for SUM_INT, MAX_COUNT, and MIN_COUNT

functions-and-operators/aggregate-group-by-functions.md

@@ -1,7 +1,7 @@
 ---
 title: GROUP BY 聚合函数
 aliases: ['/docs-cn/dev/functions-and-operators/aggregate-group-by-functions/','/docs-cn/dev/reference/sql/functions-and-operators/aggregate-group-by-functions/']
-summary: TiDB支持的聚合函数包括 COUNT、COUNT(DISTINCT)、SUM、AVG、MAX、MIN、GROUP_CONCAT、VARIANCE、VAR_POP、STD、STDDEV、VAR_SAMP、STDDEV_SAMP 和 JSON_OBJECTAGG。除了 GROUP_CONCAT 和 APPROX_PERCENTILE 外，这些聚合函数可以作为窗口函数使用。另外，TiDB 的 GROUP BY 子句支持 WITH ROLLUP 修饰符，还支持 SQL 模式 ONLY_FULL_GROUP_BY。与 MySQL 的区别在于 TiDB 对标准 SQL 有一些扩展，允许在 HAVING 子句中使用别名和非列表达式。
+summary: TiDB 支持的聚合函数包括 COUNT、COUNT(DISTINCT)、SUM、SUM_INT、MAX_COUNT、MIN_COUNT、AVG、MAX、MIN、GROUP_CONCAT、VARIANCE、VAR_POP、STD、STDDEV、VAR_SAMP、STDDEV_SAMP 和 JSON_OBJECTAGG。除了 GROUP_CONCAT、APPROX_PERCENTILE 和 APPROX_COUNT_DISTINCT 外，这些聚合函数可以作为窗口函数使用。另外，TiDB 的 GROUP BY 子句支持 WITH ROLLUP 修饰符，还支持 SQL 模式 ONLY_FULL_GROUP_BY。与 MySQL 的区别在于 TiDB 对标准 SQL 有一些扩展，允许在 HAVING 子句中使用别名和非列表达式。
 ---
 
 # GROUP BY 聚合函数
@@ -35,6 +35,114 @@ TiDB 支持的 MySQL `GROUP BY` 聚合函数如下所示：
 
 另外，TiDB 还支持以下聚合函数：
 
++ `SUM_INT(expr)`
+
+    该函数用于对整数表达式 `expr` 求和，功能类似于 `SUM(expr)`，但仅接受整数类型参数，包括有符号和无符号的 `TINYINT`、`SMALLINT`、`MEDIUMINT`、`INT` 和 `BIGINT`。对于有符号整数参数，返回类型为 `BIGINT`；对于无符号整数参数，返回类型为 `BIGINT UNSIGNED`。如果参与计算的非 `NULL` 值之和超出返回类型范围，TiDB 返回整数溢出错误。
+
+    `SUM_INT()` 忽略 `NULL` 值。如果没有非 `NULL` 值，返回 `NULL`。`SUM_INT()` 支持 `DISTINCT`，并可作为[窗口函数](/functions-and-operators/window-functions.md)使用。
+
+    以下是一个使用该函数的示例：
+
+    ```sql
+    DROP TABLE IF EXISTS t;
+    CREATE TABLE t(id INT PRIMARY KEY, a BIGINT, b BIGINT UNSIGNED);
+    INSERT INTO t VALUES(1, 1, 1), (2, 1, 1), (3, 2, 2), (4, NULL, NULL);
+    ```
+
+    ```sql
+    SELECT SUM_INT(a), SUM_INT(DISTINCT a), SUM_INT(b) FROM t;
+    ```
+
+    ```sql
+    +------------+---------------------+------------+
+    | SUM_INT(a) | SUM_INT(DISTINCT a) | SUM_INT(b) |
+    +------------+---------------------+------------+
+    |          4 |                   3 |          4 |
+    +------------+---------------------+------------+
+    1 row in set (0.00 sec)
+    ```
+
+    以下示例将 `SUM_INT()` 作为窗口函数使用：
+
+    ```sql
+    SELECT id, a, SUM_INT(a) OVER (ORDER BY id ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) AS rolling_sum
+    FROM t
+    ORDER BY id;
+    ```
+
+    ```sql
+    +----+------+-------------+
+    | id | a    | rolling_sum |
+    +----+------+-------------+
+    |  1 |    1 |           1 |
+    |  2 |    1 |           2 |
+    |  3 |    2 |           3 |
+    |  4 | NULL |           2 |
+    +----+------+-------------+
+    4 rows in set (0.00 sec)
+    ```
+
++ `MAX_COUNT([ALL] expr)` 和 `MIN_COUNT([ALL] expr)`
+
+    这两个函数是 TiDB 特有的聚合函数，用于统计组内最大值或最小值的出现次数。`MAX_COUNT(expr)` 返回 `expr` 的最大非 `NULL` 值在当前组中出现的行数；`MIN_COUNT(expr)` 返回 `expr` 的最小非 `NULL` 值在当前组中出现的行数。
+
+    这两个函数默认忽略 `NULL` 值。如果当前组中没有非 `NULL` 值，返回 `0`。返回类型为 `BIGINT`。这两个函数支持省略 `ALL` 或显式指定 `ALL`，但不支持 `DISTINCT`。例如，`MAX_COUNT(DISTINCT expr)` 和 `MIN_COUNT(DISTINCT expr)` 会返回语法错误。这两个函数也可作为[窗口函数](/functions-and-operators/window-functions.md)使用。
+
+    以下是一个使用这两个函数的示例：
+
+    ```sql
+    DROP TABLE IF EXISTS t;
+    CREATE TABLE t(a INT);
+    INSERT INTO t VALUES(1), (1), (2), (2), (2), (NULL);
+    ```
+
+    ```sql
+    SELECT MAX_COUNT(a), MIN_COUNT(a) FROM t;
+    ```
+
+    ```sql
+    +--------------+--------------+
+    | MAX_COUNT(a) | MIN_COUNT(a) |
+    +--------------+--------------+
+    |            3 |            2 |
+    +--------------+--------------+
+    1 row in set (0.00 sec)
+    ```
+
+    如果没有非 `NULL` 值，函数返回 `0`：
+
+    ```sql
+    SELECT MAX_COUNT(a), MIN_COUNT(a) FROM t WHERE a IS NULL;
+    ```
+
+    ```sql
+    +--------------+--------------+
+    | MAX_COUNT(a) | MIN_COUNT(a) |
+    +--------------+--------------+
+    |            0 |            0 |
+    +--------------+--------------+
+    1 row in set (0.00 sec)
+    ```
+
+    以下示例将 `MAX_COUNT()` 和 `MIN_COUNT()` 作为窗口函数使用：
+
+    ```sql
+    SELECT
+        MAX_COUNT(a) OVER () AS max_count,
+        MIN_COUNT(a) OVER () AS min_count
+    FROM t
+    LIMIT 1;
+    ```
+
+    ```sql
+    +-----------+-----------+
+    | max_count | min_count |
+    +-----------+-----------+
+    |         3 |         2 |
+    +-----------+-----------+
+    1 row in set (0.00 sec)
+    ```
+
 + `APPROX_PERCENTILE(expr, constant_integer_expr)`
 
     该函数用于计算 `expr` 值的百分位数。参数 `constant_integer_expr` 是一个取值为区间 `[1,100]` 内整数的常量表达式，表示百分数。一个百分位数 P<sub>k</sub>（`k`为百分数）表示数据集中至少有 `k%` 的数据小于等于 P<sub>k</sub>。
@@ -88,7 +196,7 @@ TiDB 支持的 MySQL `GROUP BY` 聚合函数如下所示：
     2 rows in set (0.00 sec)
     ```
 
-上述聚合函数除 `GROUP_CONCAT()`、 `APPROX_PERCENTILE()` 和 `APPROX_COUNT_DISTINCT` 以外，均可作为[窗口函数](/functions-and-operators/window-functions.md)使用。
+上述聚合函数除 `GROUP_CONCAT()`、`APPROX_PERCENTILE()` 和 `APPROX_COUNT_DISTINCT()` 以外，均可作为[窗口函数](/functions-and-operators/window-functions.md)使用。
 
 ## GROUP BY 修饰符
 

functions-and-operators/expressions-pushed-down.md

@@ -26,7 +26,7 @@ TiFlash 也支持[本页](/tiflash/tiflash-supported-pushdown-calculations.md)
 | [JSON 运算](/functions-and-operators/json-functions.md) | [JSON_ARRAY_APPEND()](/functions-and-operators/json-functions/json-functions-modify.md#json_array_append) <br/>[JSON_ARRAY()](/functions-and-operators/json-functions/json-functions-create.md#json_array) <br/>[JSON_CONTAINS()](/functions-and-operators/json-functions/json-functions-search.md#json_contains) <br/>[JSON_EXTRACT()](/functions-and-operators/json-functions/json-functions-search.md#json_extract) <br/>[JSON_INSERT()](/functions-and-operators/json-functions/json-functions-modify.md#json_insert) <br/>[JSON_LENGTH()](/functions-and-operators/json-functions/json-functions-return.md#json_length) <br/>[JSON_MERGE_PATCH()](/functions-and-operators/json-functions/json-functions-modify.md#json_merge_patch) <br/>[JSON_MERGE()](/functions-and-operators/json-functions/json-functions-modify.md#json_merge) <br/>[JSON_OBJECT()](/functions-and-operators/json-functions/json-functions-create.md#json_object) <br/>[JSON_REMOVE()](/functions-and-operators/json-functions/json-functions-modify.md#json_remove) <br/>[JSON_REPLACE()](/functions-and-operators/json-functions/json-functions-modify.md#json_replace) <br/>[JSON_SET()](/functions-and-operators/json-functions/json-functions-modify.md#json_set) <br/>[JSON_TYPE()](/functions-and-operators/json-functions/json-functions-return.md#json_type) <br/>[JSON_UNQUOTE()](/functions-and-operators/json-functions/json-functions-modify.md#json_unquote) <br/>[JSON_VALID()](/functions-and-operators/json-functions/json-functions-return.md#json_valid) <br/>[MEMBER OF()](/functions-and-operators/json-functions/json-functions-search.md#member-of) |
 | [日期运算](/functions-and-operators/date-and-time-functions.md) | [DATE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date) <br/>[DATE_FORMAT()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format) <br/>[DATEDIFF()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_datediff) <br/>[DAYOFMONTH()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_dayofmonth) <br/>[DAYOFWEEK()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_dayofweek) <br/>[DAYOFYEAR()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_dayofyear) <br/>[FROM_DAYS()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_from-days) <br/>[HOUR()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_hour) <br/>[MAKEDATE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_makedate) <br/>[MAKETIME()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_maketime) <br/>[MICROSECOND()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_microsecond) <br/>[MINUTE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_minute) <br/>[MONTH()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_month) <br/>[MONTHNAME()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_monthname) <br/>[PERIOD_ADD()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_period-add) <br/>[PERIOD_DIFF()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_period-diff) <br/>[SEC_TO_TIME()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_sec-to-time) <br/>[SECOND()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_second) <br/>[SYSDATE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_sysdate) <br/>[TIME_TO_SEC()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_time-to-sec) <br/>[TIMEDIFF()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_timediff) <br/>[WEEK()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_week) <br/>[WEEKOFYEAR()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_weekofyear) <br/>[YEAR()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_year) <br/>[DATE_ADD()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-add) <br/>[DATE_SUB()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-sub) <br/>[ADDDATE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_adddate) <br/>[SUBDATE()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_subdate) <br/>[FROM_UNIXTIME()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_from-unixtime) <br/>[TIMESTAMPDIFF()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_timestampdiff) <br/>[UNIX_TIMESTAMP()](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_unix-timestamp) |
 | [字符串函数](/functions-and-operators/string-functions.md) | [ASCII()](/functions-and-operators/string-functions.md#ascii) <br/>[BIT_LENGTH()](/functions-and-operators/string-functions.md#bit_length) <br/>[CHAR()](/functions-and-operators/string-functions.md#char) <br/>[CHAR_LENGTH()](/functions-and-operators/string-functions.md#char_length) <br/>[CONCAT()](/functions-and-operators/string-functions.md#concat) <br/>[CONCAT_WS()](/functions-and-operators/string-functions.md#concat_ws) <br/>[ELT()](/functions-and-operators/string-functions.md#elt) <br/>[FIELD()](/functions-and-operators/string-functions.md#field) <br/>[HEX()](/functions-and-operators/string-functions.md#hex) <br/>[LENGTH()](/functions-and-operators/string-functions.md#length) <br/>[LIKE](/functions-and-operators/string-functions.md#like) <br/>[LOWER()](/functions-and-operators/string-functions.md#lower) <br/>[LTRIM()](/functions-and-operators/string-functions.md#ltrim) <br/>[MID()](/functions-and-operators/string-functions.md#mid) <br/>[NOT LIKE](/functions-and-operators/string-functions.md#not-like) <br/>[NOT REGEXP](/functions-and-operators/string-functions.md#not-regexp) <br/>[REGEXP](/functions-and-operators/string-functions.md#regexp) <br/>[REGEXP_LIKE()](/functions-and-operators/string-functions.md#regexp_like) <br/>[REGEXP_REPLACE()](/functions-and-operators/string-functions.md#regexp_replace) <br/>[REGEXP_SUBSTR()](/functions-and-operators/string-functions.md#regexp_substr) <br/>[REPLACE()](/functions-and-operators/string-functions.md#replace) <br/>[REVERSE()](/functions-and-operators/string-functions.md#reverse) <br/>[RIGHT()](/functions-and-operators/string-functions.md#right), [RLIKE](/functions-and-operators/string-functions.md#rlike) <br/>[RTRIM()](/functions-and-operators/string-functions.md#rtrim) <br/>[SPACE()](/functions-and-operators/string-functions.md#space) <br/>[STRCMP()](/functions-and-operators/string-functions.md#strcmp) <br/>[SUBSTR()](/functions-and-operators/string-functions.md#substr) <br/>[SUBSTRING()](/functions-and-operators/string-functions.md#substring) <br/>[UPPER()](/functions-and-operators/string-functions.md#upper) |
-| [聚合函数](/functions-and-operators/aggregate-group-by-functions.md#group-by-聚合函数) | [COUNT()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_count) <br/>[COUNT(DISTINCT)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_count-distinct) <br/>[SUM()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_sum) <br/>[AVG()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_avg) <br/>[MAX()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_max) <br/>[MIN()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_min) <br/>[VARIANCE()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_variance) <br/>[VAR_POP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_var-pop) <br/>[STD()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_std) <br/>[STDDEV()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev) <br/>[STDDEV_POP](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev-pop) <br/>[VAR_SAMP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_var-samp) <br/>[STDDEV_SAMP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev-samp) <br/>[JSON_ARRAYAGG(key)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_json-arrayagg) <br/>[JSON_OBJECTAGG(key, value)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_json-objectagg) |
+| [聚合函数](/functions-and-operators/aggregate-group-by-functions.md#group-by-聚合函数) | [COUNT()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_count) <br/>[COUNT(DISTINCT)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_count-distinct) <br/>[SUM()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_sum) <br/>[`SUM_INT()`](/functions-and-operators/aggregate-group-by-functions.md) <br/>[AVG()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_avg) <br/>[MAX()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_max) <br/>[MIN()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_min) <br/>[VARIANCE()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_variance) <br/>[VAR_POP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_var-pop) <br/>[STD()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_std) <br/>[STDDEV()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev) <br/>[STDDEV_POP](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev-pop) <br/>[VAR_SAMP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_var-samp) <br/>[STDDEV_SAMP()](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_stddev-samp) <br/>[JSON_ARRAYAGG(key)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_json-arrayagg) <br/>[JSON_OBJECTAGG(key, value)](https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html#function_json-objectagg) |
 | [加密和压缩函数](/functions-and-operators/encryption-and-compression-functions.md#加密和压缩函数) | [MD5()](/functions-and-operators/encryption-and-compression-functions.md#md5) <br/>[SHA1(), SHA()](/functions-and-operators/encryption-and-compression-functions.md#sha1) <br/>[UNCOMPRESSED_LENGTH()](/functions-and-operators/encryption-and-compression-functions.md#uncompressed_length) |
 | [Cast 函数](/functions-and-operators/cast-functions-and-operators.md#cast-函数和操作符) | [CAST()](/functions-and-operators/cast-functions-and-operators.md#cast) <br/>[CONVERT()](/functions-and-operators/cast-functions-and-operators.md#convert) |
 | [其他函数](/functions-and-operators/miscellaneous-functions.md#支持的函数) | [UUID()](/functions-and-operators/miscellaneous-functions.md#uuid) |

functions-and-operators/window-functions.md

@@ -1,7 +1,7 @@
 ---
 title: 窗口函数
 aliases: ['/docs-cn/dev/functions-and-operators/window-functions/','/docs-cn/dev/reference/sql/functions-and-operators/window-functions/']
-summary: TiDB 中的窗口函数与 MySQL 8.0 基本一致。可以将 `tidb_enable_window_function` 设置为 `0` 来解决升级后无法解析语法的问题。TiDB 支持除 `GROUP_CONCAT()` 和 `APPROX_PERCENTILE()` 以外的所有 `GROUP BY` 聚合函数。其他支持的窗口函数包括 `CUME_DIST()`、`DENSE_RANK()`、`FIRST_VALUE()`、`LAG()`、`LAST_VALUE()`、`LEAD()`、`NTH_VALUE()`、`NTILE()`、`PERCENT_RANK()`、`RANK()` 和 `ROW_NUMBER()`。这些函数可以下推到 TiFlash。
+summary: TiDB 中的窗口函数与 MySQL 8.0 基本一致。可以将 `tidb_enable_window_function` 设置为 `0` 来解决升级后无法解析语法的问题。TiDB 支持除 `GROUP_CONCAT()`、`APPROX_PERCENTILE()` 和 `APPROX_COUNT_DISTINCT()` 以外的所有 `GROUP BY` 聚合函数作为窗口函数，包括 `SUM_INT()`、`MAX_COUNT()` 和 `MIN_COUNT()`。其他支持的窗口函数包括 `CUME_DIST()`、`DENSE_RANK()`、`FIRST_VALUE()`、`LAG()`、`LAST_VALUE()`、`LEAD()`、`NTH_VALUE()`、`NTILE()`、`PERCENT_RANK()`、`RANK()` 和 `ROW_NUMBER()`。这些函数可以下推到 TiFlash。
 ---
 
 # 窗口函数
@@ -16,7 +16,7 @@ TiDB 中窗口函数的使用方法与 MySQL 8.0 基本一致，详情可参见
 
 [本页](/tiflash/tiflash-supported-pushdown-calculations.md)列出的窗口函数可以下推到 TiFlash。
 
-TiDB 支持除 `GROUP_CONCAT()` 和 `APPROX_PERCENTILE()` 以外的所有 [`GROUP BY` 聚合函数](/functions-and-operators/aggregate-group-by-functions.md)作为窗口函数。此外，TiDB 支持的其他窗口函数如下：
+TiDB 支持除 `GROUP_CONCAT()`、`APPROX_PERCENTILE()` 和 `APPROX_COUNT_DISTINCT()` 以外的所有 [`GROUP BY` 聚合函数](/functions-and-operators/aggregate-group-by-functions.md)作为窗口函数，包括 `SUM_INT()`、`MAX_COUNT()` 和 `MIN_COUNT()`。此外，TiDB 支持的其他窗口函数如下：
 
 | 函数名 | 功能描述 |
 | :-------------- | :------------------------------------- |