improve sql parser

src/main/java/com/alibaba/druid/sql/ast/statement/SQLConstaintImpl.java

@@ -21,6 +21,7 @@ import com.alibaba.druid.sql.ast.SQLObjectImpl;
 public abstract class SQLConstaintImpl extends SQLObjectImpl implements SQLConstaint {
 
     private SQLName name;
+    private Boolean enable;
 
     public SQLConstaintImpl(){
 
@@ -34,4 +35,12 @@ public abstract class SQLConstaintImpl extends SQLObjectImpl implements SQLConst
         this.name = name;
     }
 
+    public Boolean getEnable() {
+        return enable;
+    }
+
+    public void setEnable(Boolean enable) {
+        this.enable = enable;
+    }
+
 }