diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/QueryTable.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/QueryTable.java
index 5091a48b..a90b529e 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/QueryTable.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/QueryTable.java
@@ -31,6 +31,7 @@ import java.util.Objects;
  */
 public class QueryTable implements CloneSupport<QueryTable> {
 
+
     protected String schema;
     protected String name;
     protected String alias;
diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/SelectQueryTable.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/SelectQueryTable.java
index 8947af8f..901f9c44 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/SelectQueryTable.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/query/SelectQueryTable.java
@@ -64,4 +64,8 @@ public class SelectQueryTable extends QueryTable {
         return clone;
     }
 
+    @Override
+    public String toString() {
+        return queryWrapper.toSQL();
+    }
 }
diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/table/TableDef.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/table/TableDef.java
index 1a4fa819..4627c39e 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/table/TableDef.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/table/TableDef.java
@@ -29,7 +29,14 @@ import java.util.function.Function;
  * @author 王帅
  * @since 2024-03-11
  */
-public abstract class TableDef extends QueryTable {
+public class TableDef extends QueryTable {
+
+    private static final Map<String, TableDef> CACHE = new ConcurrentHashMap<>();
+
+    @SuppressWarnings("unchecked")
+    protected static <V extends TableDef> V getCache(String key, Function<String, V> mappingFunction) {
+        return MapUtil.computeIfAbsent((Map<String, V>) CACHE, key, mappingFunction);
+    }
 
     protected TableDef(String schema, String tableName) {
         super(schema, tableName);
@@ -48,11 +55,9 @@ public abstract class TableDef extends QueryTable {
         return name;
     }
 
-    private static final Map<String, TableDef> CACHE = new ConcurrentHashMap<>();
-
-    @SuppressWarnings("unchecked")
-    protected static <V extends TableDef> V getCache(String key, Function<String, V> mappingFunction) {
-        return MapUtil.computeIfAbsent((Map<String, V>) CACHE, key, mappingFunction);
+    public TableDef as(String alias) {
+        String key = getNameWithSchema() + "." + alias;
+        return getCache(key, k -> new TableDef(this.schema, this.name, alias));
     }
 
 }
diff --git a/mybatis-flex-core/src/test/java/com/mybatisflex/coretest/QueryWrapperTest.java b/mybatis-flex-core/src/test/java/com/mybatisflex/coretest/QueryWrapperTest.java
index de23fb47..8fe1cff7 100644
--- a/mybatis-flex-core/src/test/java/com/mybatisflex/coretest/QueryWrapperTest.java
+++ b/mybatis-flex-core/src/test/java/com/mybatisflex/coretest/QueryWrapperTest.java
@@ -23,9 +23,8 @@ import com.mybatisflex.core.query.QueryWrapper;
 import org.junit.Assert;
 import org.junit.Test;
 
-import static com.mybatisflex.core.query.QueryMethods.*;
 import static com.mybatisflex.coretest.table.AccountTableDef.ACCOUNT;
-import static org.junit.Assert.assertEquals;
+import static com.mybatisflex.core.query.QueryMethods.*;
 
 /**
  * Lambda 构建 SQL 测试。