diff --git a/src/main/java/com/alibaba/druid/sql/ast/statement/SQLAlterTableAddColumn.java b/src/main/java/com/alibaba/druid/sql/ast/statement/SQLAlterTableAddColumn.java
index 5f3075b517..4001665385 100644
--- a/src/main/java/com/alibaba/druid/sql/ast/statement/SQLAlterTableAddColumn.java
+++ b/src/main/java/com/alibaba/druid/sql/ast/statement/SQLAlterTableAddColumn.java
@@ -23,7 +23,7 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 
 public class SQLAlterTableAddColumn extends SQLObjectImpl implements SQLAlterTableItem {
 
-    private List<SQLColumnDefinition> columns = new ArrayList<SQLColumnDefinition>();
+    private final List<SQLColumnDefinition> columns = new ArrayList<SQLColumnDefinition>();
 
     @Override
     protected void accept0(SQLASTVisitor visitor) {
@@ -37,8 +37,4 @@ public class SQLAlterTableAddColumn extends SQLObjectImpl implements SQLAlterTab
         return columns;
     }
 
-    public void setColumns(List<SQLColumnDefinition> columns) {
-        this.columns = columns;
-    }
-
 }
diff --git a/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java b/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
index c415c7793f..4a0fc68b6c 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SchemaStatVisitor.java
@@ -47,6 +47,7 @@ import com.alibaba.druid.sql.ast.statement.SQLAlterTableEnableConstraint;
 import com.alibaba.druid.sql.ast.statement.SQLAlterTableItem;
 import com.alibaba.druid.sql.ast.statement.SQLAlterTableStatement;
 import com.alibaba.druid.sql.ast.statement.SQLCallStatement;
+import com.alibaba.druid.sql.ast.statement.SQLCheck;
 import com.alibaba.druid.sql.ast.statement.SQLColumnDefinition;
 import com.alibaba.druid.sql.ast.statement.SQLCommentStatement;
 import com.alibaba.druid.sql.ast.statement.SQLCreateIndexStatement;
@@ -1281,4 +1282,9 @@ public class SchemaStatVisitor extends SQLASTVisitorAdapter {
         }
         return false;
     }
+    
+    public boolean visit(SQLCheck x) {
+        x.getExpr().accept(this);
+        return false;
+    }
 }
diff --git a/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleAlterTableTest22.java b/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleAlterTableTest22.java
new file mode 100644
index 0000000000..52b454863f
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleAlterTableTest22.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.oracle;
+
+import java.util.List;
+
+import org.junit.Assert;
+
+import com.alibaba.druid.sql.OracleTest;
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.dialect.oracle.parser.OracleStatementParser;
+import com.alibaba.druid.sql.dialect.oracle.visitor.OracleSchemaStatVisitor;
+import com.alibaba.druid.stat.TableStat;
+import com.alibaba.druid.util.JdbcConstants;
+
+public class OracleAlterTableTest22 extends OracleTest {
+
+    public void test_0() throws Exception {
+        String sql = //
+        "ALTER TABLE employees ADD CONSTRAINT check_comp " //
+                + "   CHECK (salary + (commission_pct*salary) <= 5000)" //
+                + "   DISABLE;";
+
+        OracleStatementParser parser = new OracleStatementParser(sql);
+        List<SQLStatement> statementList = parser.parseStatementList();
+        SQLStatement stmt = statementList.get(0);
+        print(statementList);
+
+        Assert.assertEquals(1, statementList.size());
+
+        OracleSchemaStatVisitor visitor = new OracleSchemaStatVisitor();
+        stmt.accept(visitor);
+
+        System.out.println("Tables : " + visitor.getTables());
+        System.out.println("fields : " + visitor.getColumns());
+        System.out.println("coditions : " + visitor.getConditions());
+        System.out.println("relationships : " + visitor.getRelationships());
+        System.out.println("orderBy : " + visitor.getOrderByColumns());
+
+        Assert.assertEquals("ALTER TABLE employees" //
+                            + "\n\tADD CONSTRAINT check_comp CHECK (salary + commission_pct * salary <= 5000) DIABLE", //
+                            SQLUtils.toSQLString(stmt, JdbcConstants.ORACLE));
+
+        Assert.assertEquals(1, visitor.getTables().size());
+
+        Assert.assertTrue(visitor.getTables().containsKey(new TableStat.Name("employees")));
+
+        Assert.assertEquals(2, visitor.getColumns().size());
+
+        Assert.assertTrue(visitor.getColumns().contains(new TableStat.Column("employees", "salary")));
+        Assert.assertTrue(visitor.getColumns().contains(new TableStat.Column("employees", "commission_pct")));
+    }
+}
diff --git a/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleCreateTableTest29.java b/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleCreateTableTest29.java
index 9030c7813b..baee72f740 100644
--- a/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleCreateTableTest29.java
+++ b/src/test/java/com/alibaba/druid/bvt/sql/oracle/OracleCreateTableTest29.java
@@ -71,7 +71,7 @@ public class OracleCreateTableTest29 extends OracleTest {
 
         Assert.assertEquals(1, visitor.getTables().size());
 
-        Assert.assertEquals(8, visitor.getColumns().size());
+        Assert.assertEquals(7, visitor.getColumns().size());
 
         Assert.assertTrue(visitor.getColumns().contains(new TableStat.Column("dept_20", "employee_id")));
     }