From ace4d2ed18e066a0cb325d319b9b64eaab778276 Mon Sep 17 00:00:00 2001
From: wangmm0220 <wangmm0220@gmail.com>
Date: Mon, 10 Jan 2022 19:12:38 +0800
Subject: [PATCH] 
 [TD-12252]<feature>(connector,query,insert,other,tools,taosAdapter):deal with
 escape character

---
 documentation20/cn/12.taos-sql/docs.md | 21 +++++++++++++++++++++
 documentation20/en/12.taos-sql/docs.md | 21 +++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/documentation20/cn/12.taos-sql/docs.md b/documentation20/cn/12.taos-sql/docs.md
index 9f15d05cec..a626b0f293 100755
--- a/documentation20/cn/12.taos-sql/docs.md
+++ b/documentation20/cn/12.taos-sql/docs.md
@@ -1853,3 +1853,24 @@ TDengine 中的表（列）名命名规则如下：
      ```mysql 
      select jtag->'key' from (select jtag from stable) where jtag->'key'>0
      ```
+## 转义字符说明
+- 转义字符表
+
+  | 字符序列    | **代表的字符**  |
+  | :--------:     |   -------    |
+  | \'             |  单引号'      | 
+  | \"             |  双引号"      |
+  | \n             |  换行符       |
+  | \r             |  回车符       |
+  | \t             |  tab符       |
+  | \\             |  斜杠\        |
+  | \%             |  % 规则见下    |
+  | \_             |  _ 规则见下    |
+
+- 转义字符使用规则
+  1. 标识符里有转义字符（数据库名、表名、列名）
+     1. 普通标识符：    直接提示错误的标识符，因为标识符规定必须是数字、字母和下划线，并且不能以数字开头。
+     2. 反引号``标识符： 保持原样，不转义
+  2. 数据里有转义字符
+     1. 遇到上面定义的转义字符会转义（%和_见下面说明），如果没有匹配的转义字符会忽略掉转义符\。
+     2. 对于%和_，因为在like里这两个字符是通配符，所以在模式匹配like里用\%和\_表示字符里本身的%和_，如果在like模式匹配上下文之外使用\%或\_，则它们的计算结果为字符串\%和\_，而不是%和_。
\ No newline at end of file
diff --git a/documentation20/en/12.taos-sql/docs.md b/documentation20/en/12.taos-sql/docs.md
index 5cac5a78c7..052a46043b 100755
--- a/documentation20/en/12.taos-sql/docs.md
+++ b/documentation20/en/12.taos-sql/docs.md
@@ -1335,3 +1335,24 @@ Is not null supports all types of columns. Non-null expression is < > "" and onl
       
      select jtag->'key' from (select jtag from stable) where jtag->'key'>0
      ```
+## Escape character description
+- Special Character Escape Sequences
+
+  | Escape Sequence    | **Character Represented by Sequence**  |
+    | :--------:     |   -------------------   |
+  | \\'             |  A single quote (') character    | 
+  | \\"             |  A double quote (") character      |
+  | \n             |  A newline (linefeed) character       |
+  | \r             |  A carriage return character       |
+  | \t             |  A tab character       |
+  | \\\             |  A backslash (\) character        |
+  | \\%             |  A % character; see note following the table    |
+  | \\_             |  A _ character; see note following the table    |
+
+- Escape character usage rules
+  - The escape characters that in a identifier (database name, table name, column name)
+    1. Normal identifier：    The wrong identifier is prompted directly, because the identifier must be numbers, letters and underscores, and cannot start with a number.
+    2. Backquote`` identifier： Keep it as it is.
+  - The escape characters that in a data
+    3. The escape character defined above will be escaped (% and _ see the description below). If there is no matching escape character, the escape character will be ignored.
+    4. The \% and \_ sequences are used to search for literal instances of % and _ in pattern-matching contexts where they would otherwise be interpreted as wildcard characters.If you use \% or \_ outside of pattern-matching contexts, they evaluate to the strings \% and \_, not to % and _.
\ No newline at end of file
-- 
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