docs: add histogram function

docs-cn/12-taos-sql/07-function.md

@@ -278,24 +278,24 @@ SELECT HISTOGRAM(field_name，bin_type, bin_description, normalized) FROM tb_nam
 **适用于**: 表和超级表。
 
 **说明**：
-    1. bin_type 用户指定的分桶类型, 有效输入类型为"user_input“, ”linear_bin", "log_bin"。
-    2. bin_description 描述如何生成分桶区间，针对三种桶类型，分别为以下描述格式(均为 JSON 格式字符串)：       
-       - "user_input": "[1, 3, 5, 7]" 
+1. bin_type 用户指定的分桶类型, 有效输入类型为"user_input“, ”linear_bin", "log_bin"。
+2. bin_description 描述如何生成分桶区间，针对三种桶类型，分别为以下描述格式(均为 JSON 格式字符串)：       
+    - "user_input": "[1, 3, 5, 7]" 
        用户指定 bin 的具体数值。
        
-       - "linear_bin": "{"start": 0.0, "width": 5.0, "count": 5, "infinity": true}"
+    - "linear_bin": "{"start": 0.0, "width": 5.0, "count": 5, "infinity": true}"
        "start" 表示数据起始点，"width" 表示每次 bin 偏移量, "count" 为 bin 的总数，"infinity" 表示是否添加（-inf, inf）作为区间起点跟终点，
        生成区间为[-inf, 0.0, 5.0, 10.0, 15.0, 20.0, +inf]。
  
-       - "log_bin": "{"start":1.0, "factor": 2.0, "count": 5, "infinity": true}"
+    - "log_bin": "{"start":1.0, "factor": 2.0, "count": 5, "infinity": true}"
        "start" 表示数据起始点，"factor" 表示按指数递增的因子，"count" 为 bin 的总数，"infinity" 表示是否添加（-inf, inf）作为区间起点跟终点，
        生成区间为[-inf, 1.0, 2.0, 4.0, 8.0, 16.0, +inf]。
-    3. normalized 是否将返回结果归一化到 0~1 之间 。有效输入为 0 和 1。
+3. normalized 是否将返回结果归一化到 0~1 之间 。有效输入为 0 和 1。
 
 **示例**：
 
-```sql
-     taos> SELECT HISTOGRAM(voltage, "user_input", "[1,3,5,7]", 1) FROM meters;
+```mysql
+taos> SELECT HISTOGRAM(voltage, "user_input", "[1,3,5,7]", 1) FROM meters;
          histogram(voltage, "user_input", "[1,3,5,7]", 1) |
      =======================================================
      {"lower_bin":1, "upper_bin":3, "count":0.333333}     |
@@ -303,7 +303,7 @@ SELECT HISTOGRAM(field_name，bin_type, bin_description, normalized) FROM tb_nam
      {"lower_bin":5, "upper_bin":7, "count":0.333333}     |
      Query OK, 3 row(s) in set (0.004273s)
      
-     taos> SELECT HISTOGRAM(voltage, 'linear_bin', '{"start": 1, "width": 3, "count": 3, "infinity": false}', 0) FROM meters;
+taos> SELECT HISTOGRAM(voltage, 'linear_bin', '{"start": 1, "width": 3, "count": 3, "infinity": false}', 0) FROM meters;
          histogram(voltage, 'linear_bin', '{"start": 1, "width": 3, " |
      ===================================================================
      {"lower_bin":1, "upper_bin":4, "count":3}                        |
@@ -311,7 +311,7 @@ SELECT HISTOGRAM(field_name，bin_type, bin_description, normalized) FROM tb_nam
      {"lower_bin":7, "upper_bin":10, "count":3}                       |
      Query OK, 3 row(s) in set (0.004887s)
     
-     taos> SELECT HISTOGRAM(voltage, 'log_bin', '{"start": 1, "factor": 3, "count": 3, "infinity": true}', 0) FROM meters;
+taos> SELECT HISTOGRAM(voltage, 'log_bin', '{"start": 1, "factor": 3, "count": 3, "infinity": true}', 0) FROM meters;
      histogram(voltage, 'log_bin', '{"start": 1, "factor": 3, "count" |
      ===================================================================
      {"lower_bin":-inf, "upper_bin":1, "count":3}                     |

docs-en/12-taos-sql/07-function.md

@@ -275,54 +275,56 @@ SELECT HISTOGRAM(field_name，bin_type, bin_description, normalized) FROM tb_nam
 
 **Applicable table types**: table, STable
 
-**说明**：
-    1. bin_type: parameter to indicate the bucket type, valid inputs are: "user_input", "linear_bin", "log_bin"。
-    2. bin_description: parameter to describe how to generate buckets，can be in the following JSON formats for each bin_type respectively:
-       - "user_input": "[1, 3, 5, 7]"
-       User defined specified bin values.
+**Explanations**：
 
-       - "linear_bin": "{"start": 0.0, "width": 5.0, "count": 5, "infinity": true}"
+1. bin_type: parameter to indicate the bucket type, valid inputs are: "user_input", "linear_bin", "log_bin"。
+2. bin_description: parameter to describe how to generate buckets，can be in the following JSON formats for each bin_type respectively: 
+
+    - "user_input": "[1, 3, 5, 7]":  User specified bin values.
+
+    - "linear_bin": "{"start": 0.0, "width": 5.0, "count": 5, "infinity": true}"
        "start" - bin starting point.
        "width" - bin offset.
        "count" - number of bins generated.
        "infinity" - whether to add（-inf, inf）as start/end point in generated set of bins.
        The above "linear_bin" descriptor generates a set of bins: [-inf, 0.0, 5.0, 10.0, 15.0, 20.0, +inf].
 
-       - "log_bin": "{"start":1.0, "factor": 2.0, "count": 5, "infinity": true}"
+    - "log_bin": "{"start":1.0, "factor": 2.0, "count": 5, "infinity": true}"
        "start" - bin starting point.
        "factor" - exponential factor of bin offset.
        "count" - number of bins generated.
        "infinity" - whether to add（-inf, inf）as start/end point in generated range of bins.
        The above "log_bin" descriptor generates a set of bins:[-inf, 1.0, 2.0, 4.0, 8.0, 16.0, +inf].
-    3. normalized: setting to 1/0 to turn on/off result normalization.
 
-**示例**：
+3. normalized: setting to 1/0 to turn on/off result normalization.
 
-```sql
-     taos> SELECT HISTOGRAM(voltage, "user_input", "[1,3,5,7]", 1) FROM meters;
-         histogram(voltage, "user_input", "[1,3,5,7]", 1) |
+**Example**：
+
+```mysql
+taos> SELECT HISTOGRAM(voltage, "user_input", "[1,3,5,7]", 1) FROM meters;
+     histogram(voltage, "user_input", "[1,3,5,7]", 1) |
      =======================================================
      {"lower_bin":1, "upper_bin":3, "count":0.333333}     |
      {"lower_bin":3, "upper_bin":5, "count":0.333333}     |
      {"lower_bin":5, "upper_bin":7, "count":0.333333}     |
      Query OK, 3 row(s) in set (0.004273s)
-     
-     taos> SELECT HISTOGRAM(voltage, 'linear_bin', '{"start": 1, "width": 3, "count": 3, "infinity": false}', 0) FROM meters;
+
+taos> SELECT HISTOGRAM(voltage, 'linear_bin', '{"start": 1, "width": 3, "count": 3, "infinity": false}', 0) FROM meters;
          histogram(voltage, 'linear_bin', '{"start": 1, "width": 3, " |
      ===================================================================
      {"lower_bin":1, "upper_bin":4, "count":3}                        |
      {"lower_bin":4, "upper_bin":7, "count":3}                        |
      {"lower_bin":7, "upper_bin":10, "count":3}                       |
      Query OK, 3 row(s) in set (0.004887s)
-    
-     taos> SELECT HISTOGRAM(voltage, 'log_bin', '{"start": 1, "factor": 3, "count": 3, "infinity": true}', 0) FROM meters;
-     histogram(voltage, 'log_bin', '{"start": 1, "factor": 3, "count" |
-     ===================================================================
-     {"lower_bin":-inf, "upper_bin":1, "count":3}                     |
-     {"lower_bin":1, "upper_bin":3, "count":2}                        |
-     {"lower_bin":3, "upper_bin":9, "count":6}                        |
-     {"lower_bin":9, "upper_bin":27, "count":3}                       |
-     {"lower_bin":27, "upper_bin":inf, "count":1}                     |
+
+taos> SELECT HISTOGRAM(voltage, 'log_bin', '{"start": 1, "factor": 3, "count": 3, "infinity": true}', 0) FROM meters;
+   histogram(voltage, 'log_bin', '{"start": 1, "factor": 3, "count" |
+   ===================================================================
+   {"lower_bin":-inf, "upper_bin":1, "count":3}                     |
+   {"lower_bin":1, "upper_bin":3, "count":2}                        |
+   {"lower_bin":3, "upper_bin":9, "count":6}                        |
+   {"lower_bin":9, "upper_bin":27, "count":3}                       |
+   {"lower_bin":27, "upper_bin":inf, "count":1}                     |
 ```
 
 ## Selection Functions