MS SQL Server: add support for IDENTITY column option (#1432)

src/ast/ddl.rs

@@ -1050,6 +1050,20 @@ impl fmt::Display for ColumnOptionDef {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
+pub struct IdentityProperty {
+    pub seed: Expr,
+    pub increment: Expr,
+}
+
+impl fmt::Display for IdentityProperty {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}, {}", self.seed, self.increment)
+    }
+}
+
 /// `ColumnOption`s are modifiers that follow a column definition in a `CREATE
 /// TABLE` statement.
 #[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
@@ -1120,6 +1134,13 @@ pub enum ColumnOption {
     /// [1]: https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#view_column_option_list
     /// [2]: https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#column_option_list
     Options(Vec<SqlOption>),
+    /// MS SQL Server specific: Creates an identity column in a table.
+    /// Syntax
+    /// ```sql
+    /// IDENTITY [ (seed , increment) ]
+    /// ```
+    /// [MS SQL Server]: https://learn.microsoft.com/en-us/sql/t-sql/statements/create-table-transact-sql-identity-property
+    Identity(Option<IdentityProperty>),
 }
 
 impl fmt::Display for ColumnOption {
@@ -1221,6 +1242,13 @@ impl fmt::Display for ColumnOption {
             Options(options) => {
                 write!(f, "OPTIONS({})", display_comma_separated(options))
             }
+            Identity(parameters) => {
+                write!(f, "IDENTITY")?;
+                if let Some(parameters) = parameters {
+                    write!(f, "({parameters})")?;
+                }
+                Ok(())
+            }
         }
     }
 }

src/ast/mod.rs

@@ -36,8 +36,8 @@ pub use self::dcl::{AlterRoleOperation, ResetConfig, RoleOption, SetConfigValue,
 pub use self::ddl::{
     AlterColumnOperation, AlterIndexOperation, AlterTableOperation, ClusteredBy, ColumnDef,
     ColumnOption, ColumnOptionDef, ConstraintCharacteristics, Deduplicate, DeferrableInitial,
-    GeneratedAs, GeneratedExpressionMode, IndexOption, IndexType, KeyOrIndexDisplay, Owner,
-    Partition, ProcedureParam, ReferentialAction, TableConstraint,
+    GeneratedAs, GeneratedExpressionMode, IdentityProperty, IndexOption, IndexType,
+    KeyOrIndexDisplay, Owner, Partition, ProcedureParam, ReferentialAction, TableConstraint,
     UserDefinedTypeCompositeAttributeDef, UserDefinedTypeRepresentation, ViewColumnDef,
 };
 pub use self::dml::{CreateIndex, CreateTable, Delete, Insert};

src/parser/mod.rs

@@ -6069,6 +6069,20 @@ impl<'a> Parser<'a> {
             && dialect_of!(self is MySqlDialect | SQLiteDialect | DuckDbDialect | GenericDialect)
         {
             self.parse_optional_column_option_as()
+        } else if self.parse_keyword(Keyword::IDENTITY)
+            && dialect_of!(self is MsSqlDialect | GenericDialect)
+        {
+            let property = if self.consume_token(&Token::LParen) {
+                let seed = self.parse_number()?;
+                self.expect_token(&Token::Comma)?;
+                let increment = self.parse_number()?;
+                self.expect_token(&Token::RParen)?;
+
+                Some(IdentityProperty { seed, increment })
+            } else {
+                None
+            };
+            Ok(Some(ColumnOption::Identity(property)))
         } else {
             Ok(None)
         }