From 7805f333d6045ea3c4389cb00488c677b2a25653 Mon Sep 17 00:00:00 2001
From: Yoav Cohen <yoav@satoricyber.com>
Date: Sun, 29 Jun 2025 21:45:20 +0200
Subject: [PATCH] Add support for NULL escape char in pattern match searches

---
 src/ast/mod.rs            | 12 ++++++------
 src/parser/mod.rs         |  4 ++--
 tests/sqlparser_common.rs | 25 +++++++++++++++++++++----
 3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/src/ast/mod.rs b/src/ast/mod.rs
index 19966d21c..df96bff89 100644
--- a/src/ast/mod.rs
+++ b/src/ast/mod.rs
@@ -809,7 +809,7 @@ pub enum Expr {
         any: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<String>,
+        escape_char: Option<Value>,
     },
     /// `ILIKE` (case-insensitive `LIKE`)
     ILike {
@@ -819,14 +819,14 @@ pub enum Expr {
         any: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<String>,
+        escape_char: Option<Value>,
     },
     /// SIMILAR TO regex
     SimilarTo {
         negated: bool,
         expr: Box<Expr>,
         pattern: Box<Expr>,
-        escape_char: Option<String>,
+        escape_char: Option<Value>,
     },
     /// MySQL: RLIKE regex or REGEXP regex
     RLike {
@@ -1486,7 +1486,7 @@ impl fmt::Display for Expr {
             } => match escape_char {
                 Some(ch) => write!(
                     f,
-                    "{} {}LIKE {}{} ESCAPE '{}'",
+                    "{} {}LIKE {}{} ESCAPE {}",
                     expr,
                     if *negated { "NOT " } else { "" },
                     if *any { "ANY " } else { "" },
@@ -1511,7 +1511,7 @@ impl fmt::Display for Expr {
             } => match escape_char {
                 Some(ch) => write!(
                     f,
-                    "{} {}ILIKE {}{} ESCAPE '{}'",
+                    "{} {}ILIKE {}{} ESCAPE {}",
                     expr,
                     if *negated { "NOT " } else { "" },
                     if *any { "ANY" } else { "" },
@@ -1566,7 +1566,7 @@ impl fmt::Display for Expr {
             } => match escape_char {
                 Some(ch) => write!(
                     f,
-                    "{} {}SIMILAR TO {} ESCAPE '{}'",
+                    "{} {}SIMILAR TO {} ESCAPE {}",
                     expr,
                     if *negated { "NOT " } else { "" },
                     pattern,
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index a079488f8..4f0fd55d3 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -3642,9 +3642,9 @@ impl<'a> Parser<'a> {
     }
 
     /// Parse the `ESCAPE CHAR` portion of `LIKE`, `ILIKE`, and `SIMILAR TO`
-    pub fn parse_escape_char(&mut self) -> Result<Option<String>, ParserError> {
+    pub fn parse_escape_char(&mut self) -> Result<Option<Value>, ParserError> {
         if self.parse_keyword(Keyword::ESCAPE) {
-            Ok(Some(self.parse_literal_string()?))
+            Ok(Some(self.parse_value()?.into()))
         } else {
             Ok(None)
         }
diff --git a/tests/sqlparser_common.rs b/tests/sqlparser_common.rs
index f6f51459c..befa4cb3f 100644
--- a/tests/sqlparser_common.rs
+++ b/tests/sqlparser_common.rs
@@ -2040,7 +2040,7 @@ fn parse_ilike() {
                 pattern: Box::new(Expr::Value(
                     (Value::SingleQuotedString("%a".to_string())).with_empty_span()
                 )),
-                escape_char: Some('^'.to_string()),
+                escape_char: Some(Value::SingleQuotedString('^'.to_string())),
                 any: false,
             },
             select.selection.unwrap()
@@ -2104,7 +2104,7 @@ fn parse_like() {
                 pattern: Box::new(Expr::Value(
                     (Value::SingleQuotedString("%a".to_string())).with_empty_span()
                 )),
-                escape_char: Some('^'.to_string()),
+                escape_char: Some(Value::SingleQuotedString('^'.to_string())),
                 any: false,
             },
             select.selection.unwrap()
@@ -2167,7 +2167,24 @@ fn parse_similar_to() {
                 pattern: Box::new(Expr::Value(
                     (Value::SingleQuotedString("%a".to_string())).with_empty_span()
                 )),
-                escape_char: Some('^'.to_string()),
+                escape_char: Some(Value::SingleQuotedString('^'.to_string())),
+            },
+            select.selection.unwrap()
+        );
+
+        let sql = &format!(
+            "SELECT * FROM customers WHERE name {}SIMILAR TO '%a' ESCAPE NULL",
+            if negated { "NOT " } else { "" }
+        );
+        let select = verified_only_select(sql);
+        assert_eq!(
+            Expr::SimilarTo {
+                expr: Box::new(Expr::Identifier(Ident::new("name"))),
+                negated,
+                pattern: Box::new(Expr::Value(
+                    (Value::SingleQuotedString("%a".to_string())).with_empty_span()
+                )),
+                escape_char: Some(Value::Null),
             },
             select.selection.unwrap()
         );
@@ -2185,7 +2202,7 @@ fn parse_similar_to() {
                 pattern: Box::new(Expr::Value(
                     (Value::SingleQuotedString("%a".to_string())).with_empty_span()
                 )),
-                escape_char: Some('^'.to_string()),
+                escape_char: Some(Value::SingleQuotedString('^'.to_string())),
             })),
             select.selection.unwrap()
         );