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new 39228d4ed60 [SPARK-45361][SQL][DOCS] Describe characters unescaping in
string literals
39228d4ed60 is described below
commit 39228d4ed60de18a57915ede12013f415d5471aa
Author: Max Gekk <[email protected]>
AuthorDate: Mon Oct 2 23:16:55 2023 -0700
[SPARK-45361][SQL][DOCS] Describe characters unescaping in string literals
### What changes were proposed in this pull request?
In the PR, I propose to update the doc
([link](https://spark.apache.org/docs/latest/sql-ref-literals.html#string-literal))
about string literals, and describe unescaping.
<img width="1193" alt="Screenshot 2023-09-28 at 21 23 01"
src="https://github.com/apache/spark/assets/1580697/7b871ded-50e1-4c93-9d86-60a2ce93f5e7";>
### Why are the changes needed?
To make clear how string literals are preprocessed. This should less
confuse Spark SQL users.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
By building docs.
### Was this patch authored or co-authored using generative AI tooling?
No.
Closes #43152 from MaxGekk/doc-string-literal.
Authored-by: Max Gekk <[email protected]>
Signed-off-by: Dongjoon Hyun <[email protected]>
---
docs/sql-ref-literals.md | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/docs/sql-ref-literals.md b/docs/sql-ref-literals.md
index 44164d94fdc..e9447af71c5 100644
--- a/docs/sql-ref-literals.md
+++ b/docs/sql-ref-literals.md
@@ -51,6 +51,17 @@ A string literal is used to specify a character string value.
Case insensitive, indicates `RAW`. If a string literal starts with `r`
prefix, neither special characters nor unicode characters are escaped by `\`.
+The following escape sequences are recognized in regular string literals
(without the `r` prefix), and replaced according to the following rules:
+- `\0` -> `\u0000`, unicode character with the code 0;
+- `\b` -> `\u0008`, backspace;
+- `\n` -> `\u000a`, linefeed;
+- `\r` -> `\u000d`, carriage return;
+- `\t` -> `\u0009`, horizontal tab;
+- `\Z` -> `\u001A`, substitute;
+- `\%` -> `\%`;
+- `\_` -> `\_`;
+- `\<other char>` -> `<other char>`, skip the slash and leave the character as
is.
+
#### Examples
```sql
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