Add support for "on delete cascade" column option (#170)

Specifically, `FOREIGN KEY REFERENCES <foreign_table> (<referred_columns>)`
can now be followed by `ON DELETE <referential_action>` and/or by
`ON UPDATE <referential_action>`.

src/ast/ddl.rs

@@ -155,10 +155,15 @@ pub enum ColumnOption {
         is_primary: bool,
     },
     /// A referential integrity constraint (`[FOREIGN KEY REFERENCES
-    /// <foreign_table> (<referred_columns>)`).
+    /// <foreign_table> (<referred_columns>)
+    /// { [ON DELETE <referential_action>] [ON UPDATE <referential_action>] |
+    ///   [ON UPDATE <referential_action>] [ON DELETE <referential_action>]
+    /// }`).
     ForeignKey {
         foreign_table: ObjectName,
         referred_columns: Vec<Ident>,
+        on_delete: Option<ReferentialAction>,
+        on_update: Option<ReferentialAction>,
     },
     // `CHECK (<expr>)`
     Check(Expr),
@@ -177,12 +182,21 @@ impl fmt::Display for ColumnOption {
             ForeignKey {
                 foreign_table,
                 referred_columns,
-            } => write!(
+                on_delete,
-                f,
+                on_update,
-                "REFERENCES {} ({})",
+            } => {
-                foreign_table,
+                write!(f, "REFERENCES {}", foreign_table)?;
-                display_comma_separated(referred_columns)
+                if !referred_columns.is_empty() {
-            ),
+                    write!(f, " ({})", display_comma_separated(referred_columns))?;
+                }
+                if let Some(action) = on_delete {
+                    write!(f, " ON DELETE {}", action)?;
+                }
+                if let Some(action) = on_update {
+                    write!(f, " ON UPDATE {}", action)?;
+                }
+                Ok(())
+            }
             Check(expr) => write!(f, "CHECK ({})", expr),
         }
     }
@@ -200,3 +214,28 @@ fn display_constraint_name<'a>(name: &'a Option<Ident>) -> impl fmt::Display + '
     }
     ConstraintName(name)
 }
+
+/// `<referential_action> =
+/// { RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT }`
+///
+/// Used in foreign key constraints in `ON UPDATE` and `ON DELETE` options.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum ReferentialAction {
+    Restrict,
+    Cascade,
+    SetNull,
+    NoAction,
+    SetDefault,
+}
+
+impl fmt::Display for ReferentialAction {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(match self {
+            ReferentialAction::Restrict => "RESTRICT",
+            ReferentialAction::Cascade => "CASCADE",
+            ReferentialAction::SetNull => "SET NULL",
+            ReferentialAction::NoAction => "NO ACTION",
+            ReferentialAction::SetDefault => "SET DEFAULT",
+        })
+    }
+}

src/ast/mod.rs

@@ -22,7 +22,8 @@ use std::fmt;
 
 pub use self::data_type::DataType;
 pub use self::ddl::{
-    AlterTableOperation, ColumnDef, ColumnOption, ColumnOptionDef, TableConstraint,
+    AlterTableOperation, ColumnDef, ColumnOption, ColumnOptionDef, ReferentialAction,
+    TableConstraint,
 };
 pub use self::operator::{BinaryOperator, UnaryOperator};
 pub use self::query::{

src/dialect/keywords.rs

@@ -51,6 +51,7 @@ macro_rules! define_keywords {
 
 define_keywords!(
     ABS,
+    ACTION,
     ADD,
     ASC,
     ALL,

src/parser.rs

@@ -1038,10 +1038,25 @@ impl Parser {
             ColumnOption::Unique { is_primary: false }
         } else if self.parse_keyword("REFERENCES") {
             let foreign_table = self.parse_object_name()?;
-            let referred_columns = self.parse_parenthesized_column_list(Mandatory)?;
+            // PostgreSQL allows omitting the column list and
+            // uses the primary key column of the foreign table by default
+            let referred_columns = self.parse_parenthesized_column_list(Optional)?;
+            let mut on_delete = None;
+            let mut on_update = None;
+            loop {
+                if on_delete.is_none() && self.parse_keywords(vec!["ON", "DELETE"]) {
+                    on_delete = Some(self.parse_referential_action()?);
+                } else if on_update.is_none() && self.parse_keywords(vec!["ON", "UPDATE"]) {
+                    on_update = Some(self.parse_referential_action()?);
+                } else {
+                    break;
+                }
+            }
             ColumnOption::ForeignKey {
                 foreign_table,
                 referred_columns,
+                on_delete,
+                on_update,
             }
         } else if self.parse_keyword("CHECK") {
             self.expect_token(&Token::LParen)?;
@@ -1055,6 +1070,25 @@ impl Parser {
         Ok(ColumnOptionDef { name, option })
     }
 
+    pub fn parse_referential_action(&mut self) -> Result<ReferentialAction, ParserError> {
+        if self.parse_keyword("RESTRICT") {
+            Ok(ReferentialAction::Restrict)
+        } else if self.parse_keyword("CASCADE") {
+            Ok(ReferentialAction::Cascade)
+        } else if self.parse_keywords(vec!["SET", "NULL"]) {
+            Ok(ReferentialAction::SetNull)
+        } else if self.parse_keywords(vec!["NO", "ACTION"]) {
+            Ok(ReferentialAction::NoAction)
+        } else if self.parse_keywords(vec!["SET", "DEFAULT"]) {
+            Ok(ReferentialAction::SetDefault)
+        } else {
+            self.expected(
+                "one of RESTRICT, CASCADE, SET NULL, NO ACTION or SET DEFAULT",
+                self.peek_token(),
+            )
+        }
+    }
+
     pub fn parse_optional_table_constraint(
         &mut self,
     ) -> Result<Option<TableConstraint>, ParserError> {

tests/sqlparser_common.rs

@@ -893,7 +893,9 @@ fn parse_create_table() {
                lat DOUBLE NULL,\
                lng DOUBLE,
                constrained INT NULL CONSTRAINT pkey PRIMARY KEY NOT NULL UNIQUE CHECK (constrained > 0),
-               ref INT REFERENCES othertable (a, b))";
+               ref INT REFERENCES othertable (a, b),\
+               ref2 INT references othertable2 on delete cascade on update no action\
+               )";
     let ast = one_statement_parses_to(
         sql,
         "CREATE TABLE uk_cities (\
@@ -901,7 +903,8 @@ fn parse_create_table() {
          lat double NULL, \
          lng double, \
          constrained int NULL CONSTRAINT pkey PRIMARY KEY NOT NULL UNIQUE CHECK (constrained > 0), \
-         ref int REFERENCES othertable (a, b))",
+         ref int REFERENCES othertable (a, b), \
+         ref2 int REFERENCES othertable2 ON DELETE CASCADE ON UPDATE NO ACTION)",
     );
     match ast {
         Statement::CreateTable {
@@ -978,8 +981,24 @@ fn parse_create_table() {
                             option: ColumnOption::ForeignKey {
                                 foreign_table: ObjectName(vec!["othertable".into()]),
                                 referred_columns: vec!["a".into(), "b".into(),],
+                                on_delete: None,
+                                on_update: None,
                             }
                         }]
+                    },
+                    ColumnDef {
+                        name: "ref2".into(),
+                        data_type: DataType::Int,
+                        collation: None,
+                        options: vec![ColumnOptionDef {
+                            name: None,
+                            option: ColumnOption::ForeignKey {
+                                foreign_table: ObjectName(vec!["othertable2".into()]),
+                                referred_columns: vec![],
+                                on_delete: Some(ReferentialAction::Cascade),
+                                on_update: Some(ReferentialAction::NoAction),
+                            }
+                        },]
                     }
                 ]
             );
@@ -996,6 +1015,32 @@ fn parse_create_table() {
         .contains("Expected column option, found: GARBAGE"));
 }
 
+#[test]
+fn parse_create_table_with_multiple_on_delete_fails() {
+    parse_sql_statements(
+        "\
+        create table X (\
+            y_id int references Y (id) \
+            on delete cascade on update cascade on delete no action\
+        )",
+    )
+    .expect_err("should have failed");
+}
+
+#[test]
+fn parse_create_table_with_on_delete_on_update_2in_any_order() -> Result<(), ParserError> {
+    let sql = |options: &str| -> String {
+        format!("create table X (y_id int references Y (id) {})", options)
+    };
+
+    parse_sql_statements(&sql("on update cascade on delete no action"))?;
+    parse_sql_statements(&sql("on delete cascade on update cascade"))?;
+    parse_sql_statements(&sql("on update no action"))?;
+    parse_sql_statements(&sql("on delete restrict"))?;
+
+    Ok(())
+}
+
 #[test]
 fn parse_create_table_with_options() {
     let sql = "CREATE TABLE t (c int) WITH (foo = 'bar', a = 123)";