ALTER TABLE DROP {COLUMN|CONSTRAINT} RESTRICT

src/ast/ddl.rs

@@ -115,13 +115,13 @@ pub enum AlterTableOperation {
     DropConstraint {
         if_exists: bool,
         name: Ident,
-        cascade: bool,
+        drop_behavior: Option<DropBehavior>,
     },
     /// `DROP [ COLUMN ] [ IF EXISTS ] <column_name> [ CASCADE ]`
     DropColumn {
         column_name: Ident,
         if_exists: bool,
-        cascade: bool,
+        drop_behavior: Option<DropBehavior>,
     },
     /// `ATTACH PART|PARTITION <partition_expr>`
     /// Note: this is a ClickHouse-specific operation, please refer to
@@ -451,27 +451,35 @@ impl fmt::Display for AlterTableOperation {
             AlterTableOperation::DropConstraint {
                 if_exists,
                 name,
-                cascade,
+                drop_behavior,
             } => {
                 write!(
                     f,
                     "DROP CONSTRAINT {}{}{}",
                     if *if_exists { "IF EXISTS " } else { "" },
                     name,
-                    if *cascade { " CASCADE" } else { "" },
+                    match drop_behavior {
+                        None => "",
+                        Some(DropBehavior::Restrict) => " RESTRICT",
+                        Some(DropBehavior::Cascade) => " CASCADE",
+                    }
                 )
             }
             AlterTableOperation::DropPrimaryKey => write!(f, "DROP PRIMARY KEY"),
             AlterTableOperation::DropColumn {
                 column_name,
                 if_exists,
-                cascade,
+                drop_behavior,
             } => write!(
                 f,
                 "DROP COLUMN {}{}{}",
                 if *if_exists { "IF EXISTS " } else { "" },
                 column_name,
-                if *cascade { " CASCADE" } else { "" }
+                match drop_behavior {
+                    None => "",
+                    Some(DropBehavior::Restrict) => " RESTRICT",
+                    Some(DropBehavior::Cascade) => " CASCADE",
+                }
             ),
             AlterTableOperation::AttachPartition { partition } => {
                 write!(f, "ATTACH {partition}")

src/ast/spans.rs

@@ -960,12 +960,12 @@ impl Spanned for AlterTableOperation {
             AlterTableOperation::DropConstraint {
                 if_exists: _,
                 name,
-                cascade: _,
+                drop_behavior: _,
             } => name.span,
             AlterTableOperation::DropColumn {
                 column_name,
                 if_exists: _,
-                cascade: _,
+                drop_behavior: _,
             } => column_name.span,
             AlterTableOperation::AttachPartition { partition } => partition.span(),
             AlterTableOperation::DetachPartition { partition } => partition.span(),

src/parser/mod.rs

@@ -7615,11 +7615,11 @@ impl<'a> Parser<'a> {
             } else if self.parse_keyword(Keyword::CONSTRAINT) {
                 let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
                 let name = self.parse_identifier()?;
-                let cascade = self.parse_keyword(Keyword::CASCADE);
+                let drop_behavior = self.parse_optional_drop_behavior();
                 AlterTableOperation::DropConstraint {
                     if_exists,
                     name,
-                    cascade,
+                    drop_behavior,
                 }
             } else if self.parse_keywords(&[Keyword::PRIMARY, Keyword::KEY])
                 && dialect_of!(self is MySqlDialect | GenericDialect)
@@ -7637,11 +7637,11 @@ impl<'a> Parser<'a> {
                 let _ = self.parse_keyword(Keyword::COLUMN); // [ COLUMN ]
                 let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
                 let column_name = self.parse_identifier()?;
-                let cascade = self.parse_keyword(Keyword::CASCADE);
+                let drop_behavior = self.parse_optional_drop_behavior();
                 AlterTableOperation::DropColumn {
                     column_name,
                     if_exists,
-                    cascade,
+                    drop_behavior,
                 }
             }
         } else if self.parse_keyword(Keyword::PARTITION) {

tests/sqlparser_common.rs

@@ -4388,7 +4388,9 @@ fn parse_alter_table_constraints() {
 
 #[test]
 fn parse_alter_table_drop_column() {
+    check_one("DROP COLUMN IF EXISTS is_active");
     check_one("DROP COLUMN IF EXISTS is_active CASCADE");
+    check_one("DROP COLUMN IF EXISTS is_active RESTRICT");
     one_statement_parses_to(
         "ALTER TABLE tab DROP IF EXISTS is_active CASCADE",
         "ALTER TABLE tab DROP COLUMN IF EXISTS is_active CASCADE",
@@ -4403,11 +4405,15 @@ fn parse_alter_table_drop_column() {
             AlterTableOperation::DropColumn {
                 column_name,
                 if_exists,
-                cascade,
+                drop_behavior,
             } => {
                 assert_eq!("is_active", column_name.to_string());
                 assert!(if_exists);
-                assert!(cascade);
+                match drop_behavior {
+                    None => assert!(constraint_text.ends_with(" is_active")),
+                    Some(DropBehavior::Restrict) => assert!(constraint_text.ends_with(" RESTRICT")),
+                    Some(DropBehavior::Cascade) => assert!(constraint_text.ends_with(" CASCADE")),
+                }
             }
             _ => unreachable!(),
         }
@@ -4497,37 +4503,29 @@ fn parse_alter_table_alter_column_type() {
 
 #[test]
 fn parse_alter_table_drop_constraint() {
-    let alter_stmt = "ALTER TABLE tab";
-    match alter_table_op(verified_stmt(
-        "ALTER TABLE tab DROP CONSTRAINT constraint_name CASCADE",
-    )) {
-        AlterTableOperation::DropConstraint {
-            name: constr_name,
-            if_exists,
-            cascade,
-        } => {
-            assert_eq!("constraint_name", constr_name.to_string());
-            assert!(!if_exists);
-            assert!(cascade);
-        }
-        _ => unreachable!(),
-    }
-    match alter_table_op(verified_stmt(
-        "ALTER TABLE tab DROP CONSTRAINT IF EXISTS constraint_name",
-    )) {
-        AlterTableOperation::DropConstraint {
-            name: constr_name,
-            if_exists,
-            cascade,
-        } => {
-            assert_eq!("constraint_name", constr_name.to_string());
-            assert!(if_exists);
-            assert!(!cascade);
+    check_one("DROP CONSTRAINT IF EXISTS constraint_name");
+    check_one("DROP CONSTRAINT IF EXISTS constraint_name RESTRICT");
+    check_one("DROP CONSTRAINT IF EXISTS constraint_name CASCADE");
+    fn check_one(constraint_text: &str) {
+        match alter_table_op(verified_stmt(&format!("ALTER TABLE tab {constraint_text}"))) {
+            AlterTableOperation::DropConstraint {
+                name: constr_name,
+                if_exists,
+                drop_behavior,
+            } => {
+                assert_eq!("constraint_name", constr_name.to_string());
+                assert!(if_exists);
+                match drop_behavior {
+                    None => assert!(constraint_text.ends_with(" constraint_name")),
+                    Some(DropBehavior::Restrict) => assert!(constraint_text.ends_with(" RESTRICT")),
+                    Some(DropBehavior::Cascade) => assert!(constraint_text.ends_with(" CASCADE")),
+                }
+            }
+            _ => unreachable!(),
         }
-        _ => unreachable!(),
     }
 
-    let res = parse_sql_statements(&format!("{alter_stmt} DROP CONSTRAINT is_active TEXT"));
+    let res = parse_sql_statements("ALTER TABLE tab DROP CONSTRAINT is_active TEXT");
     assert_eq!(
         ParserError::ParserError("Expected: end of statement, found: TEXT".to_string()),
         res.unwrap_err()