diff --git a/README.md b/README.md
index c86bad4..b7072fd 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,10 @@ this is an oracle sql parser. ref: https://docs.oracle.com/en/database/oracle/or
 |Alter table|Modify column| :heavy_check_mark:|:heavy_check_mark:|
 |Alter table|Drop column| :heavy_check_mark:|:heavy_check_mark:|
 |Alter table|Rename column| :heavy_check_mark:|:heavy_check_mark:|
-|Alter table|Add constraint| :heavy_check_mark:| |
-|Alter table|Modify constraint| :heavy_check_mark:| |
-|Alter table|Rename constraint| :heavy_check_mark:| |
-|Alter table|Drop constraint| :heavy_check_mark:| |
+|Alter table|Add constraint| :heavy_check_mark:| :heavy_check_mark:|
+|Alter table|Modify constraint| :heavy_check_mark:| :heavy_check_mark:|
+|Alter table|Rename constraint| :heavy_check_mark:| :heavy_check_mark:|
+|Alter table|Drop constraint| :heavy_check_mark:| :heavy_check_mark:|
 |Create table|Relational table|:heavy_check_mark:|:heavy_check_mark:|
 |Create index|Relational table|:heavy_check_mark:| |
 |Drop table|-|:heavy_check_mark:|:heavy_check_mark:|
diff --git a/ast/base.go b/ast/base.go
index 29c3b95..d80ee82 100644
--- a/ast/base.go
+++ b/ast/base.go
@@ -39,7 +39,8 @@ type ColumnDefault struct {
 type ConstraintType int
 
 const (
-	ConstraintTypeNull ConstraintType = iota
+	ConstraintTypeDefault ConstraintType = iota
+	ConstraintTypeNull
 	ConstraintTypeNotNull
 	ConstraintTypeUnique
 	ConstraintTypePK
diff --git a/ast/ddl.go b/ast/ddl.go
index 92cadf9..ffcca4b 100644
--- a/ast/ddl.go
+++ b/ast/ddl.go
@@ -49,18 +49,23 @@ type RenameColumnClause struct {
 
 type AddConstraintClause struct {
 	alterTableClause
+	Constraints []*OutOfLineConstraint
 }
 
 type ModifyConstraintClause struct {
 	alterTableClause
+	Constraint *OutOfLineConstraint
 }
 
 type RenameConstraintClause struct {
 	alterTableClause
+	OldName *element.Identifier
+	NewName *element.Identifier
 }
 
 type DropConstraintClause struct {
 	alterTableClause
+	Constraint *OutOfLineConstraint
 }
 
 /*
@@ -132,4 +137,4 @@ type DropTableStmt struct {
 type DropIndexStmt struct {
 	node
 	IndexName *IndexName
-}
\ No newline at end of file
+}
diff --git a/sql.go b/sql.go
index f25644b..60cc456 100644
--- a/sql.go
+++ b/sql.go
@@ -3747,23 +3747,41 @@ yynewstate:
 		}
 	case 303:
 		{
-			yyVAL.anything = []ast.AlterTableClause{&ast.AddConstraintClause{}}
+			yyVAL.anything = []ast.AlterTableClause{&ast.AddConstraintClause{
+				Constraints: []*ast.OutOfLineConstraint{yyS[yypt-0].anything.(*ast.OutOfLineConstraint)},
+			}}
 		}
 	case 304:
 		{
-			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Name = yyS[yypt-2].anything.(*element.Identifier)
+			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+				Constraint: constraint,
+			}}
 		}
 	case 305:
 		{
-			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Type = ast.ConstraintTypePK
+			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+				Constraint: constraint,
+			}}
 		}
 	case 306:
 		{
-			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Type = ast.ConstraintTypeUnique
+			constraint.Columns = yyS[yypt-3].anything.([]*element.Identifier)
+			yyVAL.anything = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+				Constraint: constraint,
+			}}
 		}
 	case 307:
 		{
-			yyVAL.anything = []ast.AlterTableClause{&ast.RenameConstraintClause{}}
+			yyVAL.anything = []ast.AlterTableClause{&ast.RenameConstraintClause{
+				OldName: yyS[yypt-2].anything.(*element.Identifier),
+				NewName: yyS[yypt-0].anything.(*element.Identifier),
+			}}
 		}
 	case 308:
 		{
@@ -3779,15 +3797,28 @@ yynewstate:
 		}
 	case 311:
 		{
-			yyVAL.anything = &ast.DropConstraintClause{}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Type = ast.ConstraintTypePK
+			yyVAL.anything = &ast.DropConstraintClause{
+				Constraint: constraint,
+			}
 		}
 	case 312:
 		{
-			yyVAL.anything = &ast.DropConstraintClause{}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Type = ast.ConstraintTypeUnique
+			constraint.Columns = yyS[yypt-3].anything.([]*element.Identifier)
+			yyVAL.anything = &ast.DropConstraintClause{
+				Constraint: constraint,
+			}
 		}
 	case 313:
 		{
-			yyVAL.anything = &ast.DropConstraintClause{}
+			constraint := &ast.OutOfLineConstraint{}
+			constraint.Name = yyS[yypt-2].anything.(*element.Identifier)
+			yyVAL.anything = &ast.DropConstraintClause{
+				Constraint: constraint,
+			}
 		}
 	case 314:
 		{
diff --git a/sql.y b/sql.y
index a89938f..6f3312c 100644
--- a/sql.y
+++ b/sql.y
@@ -1162,24 +1162,42 @@ RenameColumnClause:
 ConstraintClauses:
     _add OutOfLineConstraint // Note: in docs is _add OutOfLineConstraints, but actual is _add OutOfLineConstraint.
     {
-    	$$ = []ast.AlterTableClause{&ast.AddConstraintClause{}}
+        $$ = []ast.AlterTableClause{&ast.AddConstraintClause{
+               Constraints: []*ast.OutOfLineConstraint{$2.(*ast.OutOfLineConstraint)},
+        }}
     }
 //|   _add OutOfLineRefConstraint
 |   _modify _constraint Identifier ConstraintState CascadeOrEmpty
     {
-    	$$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Name = $3.(*element.Identifier)
+        $$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+            Constraint: constraint,
+        }}
     }
 |   _modify _primary _key ConstraintState CascadeOrEmpty
     {
-    	$$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Type = ast.ConstraintTypePK
+        $$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+            Constraint: constraint,
+        }}
     }
 |   _modify _unique '(' ColumnNameList ')' ConstraintState CascadeOrEmpty
     {
-    	$$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{}}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Type = ast.ConstraintTypeUnique
+        constraint.Columns = $4.([]*element.Identifier)
+        $$ = []ast.AlterTableClause{&ast.ModifyConstraintClause{
+            Constraint: constraint,
+        }}
     }
 |   _rename _constraint Identifier _to Identifier
     {
-    	$$ = []ast.AlterTableClause{&ast.RenameConstraintClause{}}
+    	$$ = []ast.AlterTableClause{&ast.RenameConstraintClause{
+    	    OldName: $3.(*element.Identifier),
+    	    NewName: $5.(*element.Identifier),
+    	}}
     }
 |   DropConstraintClauses
     {
@@ -1203,15 +1221,28 @@ DropConstraintClauses:
 DropConstraintClause:
     _drop _primary _key CascadeOrEmpty DropConstraintProps
     {
-    	$$ = &ast.DropConstraintClause{}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Type = ast.ConstraintTypePK
+        $$ = &ast.DropConstraintClause{
+            Constraint: constraint,
+        }
     }
 |   _drop _unique '(' ColumnNameList ')' CascadeOrEmpty DropConstraintProps
     {
-    	$$ = &ast.DropConstraintClause{}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Type = ast.ConstraintTypeUnique
+        constraint.Columns = $4.([]*element.Identifier)
+        $$ = &ast.DropConstraintClause{
+            Constraint: constraint,
+        }
     }
 |   _drop _constraint Identifier CascadeOrEmpty DropConstraintProps
     {
-    	$$ = &ast.DropConstraintClause{}
+        constraint := &ast.OutOfLineConstraint{}
+        constraint.Name = $3.(*element.Identifier)
+        $$ = &ast.DropConstraintClause{
+            Constraint: constraint,
+        }
     }
 
 CascadeOrEmpty:
diff --git a/test/alter_table_constraint.sql b/test/alter_table_constraint.sql
index 66bff71..29244d4 100644
--- a/test/alter_table_constraint.sql
+++ b/test/alter_table_constraint.sql
@@ -16,6 +16,10 @@ alter table db1.table1 modify primary key using index;
 
 alter table db1.table1 modify primary key rely using index idx_1 enable validate;
 
+alter table db1.table1 modify constraint idx_1 using index;
+
+alter table db1.table1 modify unique(name,age) using index;
+
 alter table db1.table1 drop primary key keep index;
 
 alter table db1.table1 drop primary key keep index drop unique(name,age) drop index;
\ No newline at end of file