diff --git a/pom.xml b/pom.xml
index 672b303..a7dcb6b 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>io.github.yangziwen</groupId>
     <artifactId>quick-dao</artifactId>
-    <version>0.0.12</version>
+    <version>0.0.13-SNAPSHOT</version>
     <packaging>pom</packaging>
     <name>quick-dao</name>
     <url>http://maven.apache.org</url>
diff --git a/quick-dao-core/pom.xml b/quick-dao-core/pom.xml
index 375eb80..801a7fd 100644
--- a/quick-dao-core/pom.xml
+++ b/quick-dao-core/pom.xml
@@ -7,7 +7,7 @@
 	<parent>
 		<groupId>io.github.yangziwen</groupId>
 		<artifactId>quick-dao</artifactId>
-		<version>0.0.12</version>
+		<version>0.0.13-SNAPSHOT</version>
 	</parent>
 	<artifactId>quick-dao-core</artifactId>
 	<name>quick-dao-core</name>
diff --git a/quick-dao-core/src/main/java/io/github/yangziwen/quickdao/core/Criterion.java b/quick-dao-core/src/main/java/io/github/yangziwen/quickdao/core/Criterion.java
index 176da96..d59c4d0 100644
--- a/quick-dao-core/src/main/java/io/github/yangziwen/quickdao/core/Criterion.java
+++ b/quick-dao-core/src/main/java/io/github/yangziwen/quickdao/core/Criterion.java
@@ -1,5 +1,7 @@
 package io.github.yangziwen.quickdao.core;
 
+import java.util.Objects;
+
 import org.apache.commons.lang3.StringUtils;
 
 import io.github.yangziwen.quickdao.core.util.StringWrapper;
@@ -23,6 +25,9 @@ public class Criterion {
     @Getter
     private Operator operator = Operator.eq;
 
+    @Getter
+    private boolean valid;
+
     Criterion(String name, Criteria criteria) {
         this(name, criteria, true);
     }
@@ -30,17 +35,31 @@ public class Criterion {
     Criterion(String name, Criteria criteria, boolean valid) {
         this.name = StringUtils.replacePattern(name, "\\s+", "");
         this.criteria = criteria;
-        if (valid) {
-            criteria.getCriterionList().add(this);
-        }
+        this.valid = valid;
     }
 
     Criteria op(Operator operator, Object value) {
         this.operator = operator;
         this.value = value;
+        if (valid && !isRedundant()) {
+            criteria.getCriterionList().add(this);
+        }
         return this.criteria;
     }
 
+    private boolean isRedundant() {
+        for (Criterion criterion : criteria.getCriterionList()) {
+            if (Objects.equals(criterion.getName(), getName())
+                    && Objects.equals(criterion.getJsonField(), getJsonField())
+                    // be aware that the value comparation is based on the shallow equals
+                    && Objects.equals(criterion.getValue(), getValue())
+                    && Objects.equals(criterion.getOperator(), getOperator())) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     public Criterion jsonField(String jsonField) {
         this.jsonField = StringUtils.replacePattern(jsonField, "\\s+", "");
         return this;
diff --git a/quick-dao-example/pom.xml b/quick-dao-example/pom.xml
index 8e6342f..1fac4b1 100644
--- a/quick-dao-example/pom.xml
+++ b/quick-dao-example/pom.xml
@@ -7,7 +7,7 @@
     <parent>
         <groupId>io.github.yangziwen</groupId>
         <artifactId>quick-dao</artifactId>
-        <version>0.0.12</version>
+        <version>0.0.13-SNAPSHOT</version>
     </parent>
     <artifactId>quick-dao-example</artifactId>
     <name>quick-dao-example</name>
diff --git a/quick-dao-mybatis/pom.xml b/quick-dao-mybatis/pom.xml
index 13f0990..ff291b4 100644
--- a/quick-dao-mybatis/pom.xml
+++ b/quick-dao-mybatis/pom.xml
@@ -7,7 +7,7 @@
     <parent>
         <groupId>io.github.yangziwen</groupId>
         <artifactId>quick-dao</artifactId>
-        <version>0.0.12</version>
+        <version>0.0.13-SNAPSHOT</version>
     </parent>
     <artifactId>quick-dao-mybatis</artifactId>
     <name>quick-dao-mybatis</name>
diff --git a/quick-dao-spring-jdbc/pom.xml b/quick-dao-spring-jdbc/pom.xml
index 9c97e3a..71d0d30 100644
--- a/quick-dao-spring-jdbc/pom.xml
+++ b/quick-dao-spring-jdbc/pom.xml
@@ -7,7 +7,7 @@
     <parent>
         <groupId>io.github.yangziwen</groupId>
         <artifactId>quick-dao</artifactId>
-        <version>0.0.12</version>
+        <version>0.0.13-SNAPSHOT</version>
     </parent>
     <artifactId>quick-dao-spring-jdbc</artifactId>
     <name>quick-dao-spring-jdbc</name>
diff --git a/quick-dao-sql2o/pom.xml b/quick-dao-sql2o/pom.xml
index 75b02ca..e0129b9 100644
--- a/quick-dao-sql2o/pom.xml
+++ b/quick-dao-sql2o/pom.xml
@@ -7,7 +7,7 @@
     <parent>
         <groupId>io.github.yangziwen</groupId>
         <artifactId>quick-dao</artifactId>
-        <version>0.0.12</version>
+        <version>0.0.13-SNAPSHOT</version>
     </parent>
     <artifactId>quick-dao-sql2o</artifactId>
     <name>quick-dao-sql2o</name>