Support Modify Column for MySQL dialect (#1216)

src/ast/ddl.rs

@@ -134,6 +134,14 @@ pub enum AlterTableOperation {
         /// MySQL `ALTER TABLE` only  [FIRST | AFTER column_name]
         column_position: Option<MySQLColumnPosition>,
     },
+    // CHANGE [ COLUMN ] <col_name> <data_type> [ <options> ]
+    ModifyColumn {
+        col_name: Ident,
+        data_type: DataType,
+        options: Vec<ColumnOption>,
+        /// MySQL `ALTER TABLE` only  [FIRST | AFTER column_name]
+        column_position: Option<MySQLColumnPosition>,
+    },
     /// `RENAME CONSTRAINT <old_constraint_name> TO <new_constraint_name>`
     ///
     /// Note: this is a PostgreSQL-specific operation.
@@ -292,6 +300,22 @@ impl fmt::Display for AlterTableOperation {
 
                 Ok(())
             }
+            AlterTableOperation::ModifyColumn {
+                col_name,
+                data_type,
+                options,
+                column_position,
+            } => {
+                write!(f, "MODIFY COLUMN {col_name} {data_type}")?;
+                if !options.is_empty() {
+                    write!(f, " {}", display_separated(options, " "))?;
+                }
+                if let Some(position) = column_position {
+                    write!(f, " {position}")?;
+                }
+
+                Ok(())
+            }
             AlterTableOperation::RenameConstraint { old_name, new_name } => {
                 write!(f, "RENAME CONSTRAINT {old_name} TO {new_name}")
             }

src/keywords.rs

@@ -438,6 +438,7 @@ define_keywords!(
     MOD,
     MODE,
     MODIFIES,
+    MODIFY,
     MODULE,
     MONTH,
     MSCK,

src/parser/mod.rs

@@ -5757,6 +5757,23 @@ impl<'a> Parser<'a> {
                 options,
                 column_position,
             }
+        } else if self.parse_keyword(Keyword::MODIFY) {
+            let _ = self.parse_keyword(Keyword::COLUMN); // [ COLUMN ]
+            let col_name = self.parse_identifier(false)?;
+            let data_type = self.parse_data_type()?;
+            let mut options = vec![];
+            while let Some(option) = self.parse_optional_column_option()? {
+                options.push(option);
+            }
+
+            let column_position = self.parse_column_position()?;
+
+            AlterTableOperation::ModifyColumn {
+                col_name,
+                data_type,
+                options,
+                column_position,
+            }
         } else if self.parse_keyword(Keyword::ALTER) {
             let _ = self.parse_keyword(Keyword::COLUMN); // [ COLUMN ]
             let column_name = self.parse_identifier(false)?;