add doc of sha2()

docs/MatrixOne/Reference/Functions-and-Operators/String/sha2.md

@@ -0,0 +1,46 @@
+# **SHA2()**
+
+## **函数说明**
+
+`SHA2()` 加密函数用于计算输入字符串的 SHA2 哈希值。第一个参数是要散列的明文字符串。第二个参数指示结果的所需位长，其值必须为 224、256、384、512 或 0（相当于 256），分别对应了 SHA-224, SHA-256, SHA-384 和 SHA-512 算法。如果参数是 NULL 或者不是一个合法值将返回 NULL。
+
+## **函数语法**
+
+```
+> SHA2(str, hash_length)
+```
+
+## **参数释义**
+
+|  参数        | 说明                                  |
+|  --------   | ------------------------------------  |
+| str         | 必要参数。要计算哈希值的字符串             |
+| hash_length | 必要参数。哈希长度。                     |
+
+## **示例**
+
+```SQL
+mysql> select sha2("hello world", 384);
++--------------------------------------------------------------------------------------------------+
+| sha2(hello world, 384)                                                                           |
++--------------------------------------------------------------------------------------------------+
+| fdbd8e75a67f29f701a4e040385e2e23986303ea10239211af907fcbb83578b3e417cb71ce646efd0819dd8c088de1bd |
++--------------------------------------------------------------------------------------------------+
+1 row in set (0.00 sec)
+
+mysql> select sha2(null, 512);
++-----------------+
+| sha2(null, 512) |
++-----------------+
+| NULL            |
++-----------------+
+1 row in set (0.00 sec)
+
+mysql> select sha2("abc", 99);
++---------------+
+| sha2(abc, 99) |
++---------------+
+| NULL          |
++---------------+
+1 row in set (0.00 sec)
+```

docs/MatrixOne/Reference/Functions-and-Operators/matrixone-function-list.md

@@ -104,6 +104,7 @@
 | [REVERSE()](./String/reverse.md)               | 将 str 字符串中的字符顺序翻转输出。|
 | [RPAD()](./String/rpad.md)                     | 用于在字符串右侧填充|
 | [RTRIM()](./String/rtrim.md)                   | 将输入字符串的后方空格去除|
+| [SHA2()](./String/sha2.md)                     | 返回输入字符串的 SHA2 哈希值。|
 | [SPACE()](./String/space.md)                   | 返回 N 个空格组成的字符串。|
 | [SPLIT_PART()](./String/split_part.md)         | 用于在给定的分隔符基础上将一个字符串分解成多个部分|
 | [STARTSWITH()](./String/startswith.md)         | 字符串如果以指定前缀开始返回 1，否则则返回 0。|

mkdocs.yml

@@ -530,6 +530,7 @@ nav:
             - REVERSE(): MatrixOne/Reference/Functions-and-Operators/String/reverse.md
             - RPAD(): MatrixOne/Reference/Functions-and-Operators/String/rpad.md
             - RTRIM(): MatrixOne/Reference/Functions-and-Operators/String/rtrim.md
+            - SHA2(): MatrixOne/Reference/Functions-and-Operators/String/sha2.md
             - SPACE(): MatrixOne/Reference/Functions-and-Operators/String/space.md
             - SPLIT_PART(): MatrixOne/Reference/Functions-and-Operators/String/split_part.md
             - STARTSWITH(): MatrixOne/Reference/Functions-and-Operators/String/startswith.md