@@ -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 _.
