Support Self Joins

This required removing the equals/hashCode methods from SqlTable so
tables with the same name don't get overridden in the alias map.

Author: jeffgbutler

src/main/java/org/mybatis/dynamic/sql/SqlTable.java

@@ -45,23 +45,4 @@ public <T> SqlColumn<T> column(String name, JDBCType jdbcType, String typeHandle
     public static SqlTable of(String name) {
         return new SqlTable(name);
     }
-
-    @Override
-    public int hashCode() {
-        return Objects.hashCode(name);
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-            return true;
-        }
-
-        if (!(obj instanceof SqlTable)) {
-            return false;
-        }
-
-        SqlTable other = (SqlTable) obj;
-        return Objects.equals(name, other.name);
-    }
 }

src/test/java/examples/joins/JoinMapper.java

@@ -1,5 +1,5 @@
 /**
- *    Copyright 2016-2017 the original author or authors.
+ *    Copyright 2016-2018 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -18,7 +18,9 @@
 import java.util.List;
 import java.util.Map;
 
+import org.apache.ibatis.annotations.Result;
 import org.apache.ibatis.annotations.ResultMap;
+import org.apache.ibatis.annotations.Results;
 import org.apache.ibatis.annotations.SelectProvider;
 import org.mybatis.dynamic.sql.select.render.SelectStatementProvider;
 import org.mybatis.dynamic.sql.util.SqlProviderAdapter;
@@ -30,4 +32,12 @@ public interface JoinMapper {
 
     @SelectProvider(type=SqlProviderAdapter.class, method="select")
     List<Map<String, Object>> generalSelect(SelectStatementProvider selectStatement);
+    
+    @SelectProvider(type=SqlProviderAdapter.class, method="select")
+    @Results ({
+        @Result(column="user_id", property="userId"),
+        @Result(column="user_name", property="userName"),
+        @Result(column="parent_id", property="parentId")
+    })
+    List<User> selectUsers(SelectStatementProvider selectStatement);
 }

src/test/java/examples/joins/JoinMapperTest.java

@@ -16,10 +16,11 @@
 package examples.joins;
 
 import static examples.joins.ItemMasterDynamicSQLSupport.itemMaster;
-import static examples.joins.OrderDetailDynamicSQLSupport.orderDetail;
+import static examples.joins.OrderDetailDynamicSQLSupport.*;
 import static examples.joins.OrderLineDynamicSQLSupport.orderLine;
 import static examples.joins.OrderMasterDynamicSQLSupport.orderDate;
 import static examples.joins.OrderMasterDynamicSQLSupport.orderMaster;
+import static examples.joins.UserDynamicSQLSupport.*;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mybatis.dynamic.sql.SqlBuilder.*;
 
@@ -482,4 +483,32 @@ public void testFullJoin2() {
             assertThat(row.get("ITEM_ID")).isEqualTo(44);
         }
     }
+
+    @Test
+    public void testSelf() {
+        try (SqlSession session = sqlSessionFactory.openSession()) {
+            JoinMapper mapper = session.getMapper(JoinMapper.class);
+            
+            // get Bamm Bamm's parent - should be Barney
+            SelectStatementProvider selectStatement = select(user1.userId, user1.userName, user1.parentId)
+                    .from(user1, "u1")
+                    .join(user2, "u2").on(user1.userId, equalTo(user2.parentId))
+                    .where(user2.userId, isEqualTo(4))
+                    .build()
+                    .render(RenderingStrategy.MYBATIS3);
+            
+            String expectedStatment = "select u1.user_id, u1.user_name, u1.parent_id"
+                    + " from User u1 join User u2 on u1.user_id = u2.parent_id"
+                    + " where u2.user_id = #{parameters.p1,jdbcType=INTEGER}";
+            assertThat(selectStatement.getSelectStatement()).isEqualTo(expectedStatment);
+            
+            List<User> rows = mapper.selectUsers(selectStatement);
+
+            assertThat(rows.size()).isEqualTo(1);
+            User row = rows.get(0);
+            assertThat(row.getUserId()).isEqualTo(2);
+            assertThat(row.getUserName()).isEqualTo("Barney");
+            assertThat(row.getParentId()).isNull();
+        }
+    }
 }

src/test/java/examples/joins/User.java

@@ -0,0 +1,46 @@
+/**
+ *    Copyright 2016-2018 the original author or authors.
+ *
+ *    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 examples.joins;
+
+public class User {
+    private Integer userId;
+    private String userName;
+    private Integer parentId;
+
+    public Integer getUserId() {
+        return userId;
+    }
+
+    public void setUserId(Integer userId) {
+        this.userId = userId;
+    }
+
+    public String getUserName() {
+        return userName;
+    }
+
+    public void setUserName(String userName) {
+        this.userName = userName;
+    }
+
+    public Integer getParentId() {
+        return parentId;
+    }
+
+    public void setParentId(Integer parentId) {
+        this.parentId = parentId;
+    }
+}

src/test/java/examples/joins/UserDynamicSQLSupport.java

@@ -0,0 +1,47 @@
+/**
+ *    Copyright 2016-2018 the original author or authors.
+ *
+ *    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 examples.joins;
+
+import java.sql.JDBCType;
+
+import org.mybatis.dynamic.sql.SqlColumn;
+import org.mybatis.dynamic.sql.SqlTable;
+
+public class UserDynamicSQLSupport {
+    public static final User1 user1 = new User1();
+    public static final User2 user2 = new User2();
+   
+    
+    public static final class User1 extends SqlTable {
+        public final SqlColumn<Integer> userId = column("user_id", JDBCType.INTEGER);
+        public final SqlColumn<String> userName = column("user_name", JDBCType.VARCHAR);
+        public final SqlColumn<Integer> parentId = column("parent_id", JDBCType.INTEGER);
+        
+        public User1() {
+            super("User");
+        }
+    }
+
+    public static final class User2 extends SqlTable {
+        public final SqlColumn<Integer> userId = column("user_id", JDBCType.INTEGER);
+        public final SqlColumn<String> userName = column("user_name", JDBCType.VARCHAR);
+        public final SqlColumn<Integer> parentId = column("parent_id", JDBCType.INTEGER);
+        
+        public User2() {
+            super("User");
+        }
+    }
+}

src/test/java/org/mybatis/dynamic/sql/SqlTableTest.java

@@ -1,5 +1,5 @@
 --
---    Copyright 2016-2017 the original author or authors.
+--    Copyright 2016-2018 the original author or authors.
 --
 --    Licensed under the Apache License, Version 2.0 (the "License");
 --    you may not use this file except in compliance with the License.
@@ -18,6 +18,14 @@ drop table OrderLine if exists;
 drop table ItemMaster if exists;
 drop table OrderDetail if exists;
 drop table OrderMaster if exists;
+drop table User if exists;
+
+create table User (
+  user_id int not null,
+  user_name varchar(30) not null,
+  parent_id int null,
+  primary key (user_id)
+);
 
 create table OrderMaster (
    order_id int not null,
@@ -65,3 +73,7 @@ insert into OrderLine(order_id, item_id, line_number, quantity) values(2, 22, 1,
 insert into OrderLine(order_id, item_id, line_number, quantity) values(2, 44, 2, 1);
 insert into OrderLine(order_id, item_id, line_number, quantity) values(2, 66, 3, 6);
 
+insert into User(user_id, user_name) values(1, 'Fred');
+insert into User(user_id, user_name) values(2, 'Barney');
+insert into User(user_id, user_name, parent_id) values(3, 'Pebbles', 1);
+insert into User(user_id, user_name, parent_id) values(4, 'Bamm Bamm', 2);