String Type Literal
Description
A string is a sequence of bytes or characters enclosed in single quotes (') or double quotes ("). For example:
'a string'
"another string"
Escape Characters
In strings, certain sequences have special meanings unless the NO_BACKSLASH_ESCAPES SQL mode is enabled. These sequences start with a backslash (), which is known as an escape character. The escape characters recognized by Doris are listed in the table below:
| Escape Character | Meaning |
|---|---|
\0 | ASCII character NUL ('X'00') |
\' | Single quote (') |
\" | Double quote (") |
\b | Backspace |
\n | Newline |
\r | Carriage return |
\t | Tab |
\Z | ASCII 26 (Control+Z) |
\\ | Backslash (\) |
\% | Percent sign %. For details, see the notes below |
\_ | Underscore _. For details, see the notes below |
Notes
- In pattern matching contexts,
%and_are usually interpreted as wildcards, but using the sequences\%and\_can search for literal instances of%and_. For more information, see the description of the LIKE operator in the "Pattern Matching Operators" section. If\%or\_are used outside of pattern contexts, they will be calculated as the string\%and\_, not as%and_.- Backslashes in escape characters not listed in the table are ignored. For example,
'\y'and `'y' are equivalent.
Using Quotes in String Literals
There are several ways to include quote characters in strings:
- In a string enclosed in single quotes ('), single quotes can be written as two single quotes ('').
- In a string enclosed in double quotes ("), double quotes can be written as two double quotes (").
- Add an escape character (
\) before the quote character. - When including a single quote in a string enclosed in double quotes, no special treatment is necessary, nor must the single quote be doubled or escaped. Similarly, when including a double quote in a string enclosed in single quotes, no special treatment is required.
