!107 优化 selectCountByQuery 方法

Merge pull request !107 from 王帅/main

mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java

@@ -20,10 +20,7 @@ import com.mybatisflex.core.field.FieldQueryBuilder;
 import com.mybatisflex.core.mybatis.MappedStatementTypes;
 import com.mybatisflex.core.paginate.Page;
 import com.mybatisflex.core.provider.EntitySqlProvider;
-import com.mybatisflex.core.query.CPI;
+import com.mybatisflex.core.query.*;
-import com.mybatisflex.core.query.QueryColumn;
-import com.mybatisflex.core.query.QueryCondition;
-import com.mybatisflex.core.query.QueryWrapper;
 import com.mybatisflex.core.table.TableInfo;
 import com.mybatisflex.core.table.TableInfoFactory;
 import com.mybatisflex.core.util.*;
@@ -641,10 +638,27 @@ public interface BaseMapper<T> {
     default long selectCountByQuery(QueryWrapper queryWrapper) {
         List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
         try {
+            List<Object> objects;
             if (CollectionUtil.isEmpty(selectColumns)) {
+                // 未设置 COUNT(...) 列，默认使用 COUNT(*) 查询
                 queryWrapper.select(count());
+                objects = selectObjectListByQuery(queryWrapper);
+            } else if (selectColumns.get(0) instanceof CountQueryColumn) {
+                // 自定义 COUNT 函数，COUNT 函数必须在第一列
+                // 可以使用 COUNT(1)、COUNT(列名) 代替默认的 COUNT(*)
+                objects = selectObjectListByQuery(queryWrapper);
+            } else {
+                // 查询列中的第一列不是 COUNT 函数
+                if (MapperUtil.hasDistinct(selectColumns)) {
+                    // 查询列中包含 DISTINCT 去重
+                    // 使用子查询 SELECT COUNT(*) FROM (SELECT DISTINCT ...) AS `t`
+                    objects = selectObjectListByQuery(MapperUtil.rawCountQueryWrapper(queryWrapper));
+                } else {
+                    // 使用 COUNT(*) 替换所有的查询列
+                    queryWrapper.select(count());
+                    objects = selectObjectListByQuery(queryWrapper);
+                }
             }
-            List<Object> objects = selectObjectListByQuery(queryWrapper);
             return MapperUtil.getLongNumber(objects);
         } finally {
             //fixed https://github.com/mybatis-flex/mybatis-flex/issues/49

mybatis-flex-core/src/main/java/com/mybatisflex/core/query/CountQueryColumn.java

@@ -0,0 +1,41 @@
+/*
+ *  Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
+ *  <p>
+ *  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
+ *  <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  <p>
+ *  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.mybatisflex.core.query;
+
+import static com.mybatisflex.core.constant.FuncName.COUNT;
+
+/**
+ * COUNT 查询列。
+ *
+ * @author 王帅
+ * @since 2023-07-04
+ */
+public class CountQueryColumn extends FunctionQueryColumn {
+
+    public CountQueryColumn() {
+        super(COUNT, new StringQueryColumn("*"));
+    }
+
+    public CountQueryColumn(String column) {
+        super(COUNT, column);
+    }
+
+    public CountQueryColumn(QueryColumn column) {
+        super(COUNT, column);
+    }
+
+}

mybatis-flex-core/src/main/java/com/mybatisflex/core/query/QueryMethods.java

@@ -2158,28 +2158,28 @@ public class QueryMethods {
      * 返回指定列的总行数。
      */
     public static FunctionQueryColumn count() {
-        return new FunctionQueryColumn(COUNT, new StringQueryColumn("*"));
+        return new CountQueryColumn();
     }
 
     /**
      * 返回指定列的总行数。
      */
     public static FunctionQueryColumn count(String column) {
-        return new FunctionQueryColumn(COUNT, column);
+        return new CountQueryColumn(column);
     }
 
     /**
      * 返回指定列的总行数。
      */
     public static FunctionQueryColumn count(QueryColumn column) {
-        return new FunctionQueryColumn(COUNT, column);
+        return new CountQueryColumn(column);
     }
 
     /**
      * 返回指定列的总行数。
      */
     public static <T> FunctionQueryColumn count(LambdaGetter<T> column) {
-        return new FunctionQueryColumn(COUNT, LambdaUtil.getQueryColumn(column));
+        return new CountQueryColumn(LambdaUtil.getQueryColumn(column));
     }
 
 

mybatis-flex-core/src/main/java/com/mybatisflex/core/util/MapperUtil.java

@@ -80,7 +80,7 @@ public class MapperUtil {
         return clone;
     }
 
-    private static boolean hasDistinct(List<QueryColumn> selectColumns) {
+    public static boolean hasDistinct(List<QueryColumn> selectColumns) {
         if (CollectionUtil.isEmpty(selectColumns)) {
             return false;
         }

mybatis-flex-test/mybatis-flex-spring-boot-test/src/main/java/com/mybatisflex/test/entity/Outer.java

@@ -55,7 +55,8 @@ public class Outer extends IdEntity<Integer> {
     @Override
     public String toString() {
         return "Outer{" +
-                "name='" + name + '\'' +
+                "id='" + id + '\'' +
+                ", name='" + name + '\'' +
                 ", inner=" + inner +
                 '}';
     }

mybatis-flex-test/mybatis-flex-spring-boot-test/src/main/java/com/mybatisflex/test/model/Account.java

@@ -15,6 +15,7 @@
  */
 package com.mybatisflex.test.model;
 
+import com.mybatisflex.annotation.Column;
 import com.mybatisflex.annotation.Table;
 
 import java.util.Date;
@@ -27,6 +28,8 @@ public class Account extends BaseEntity<String, Long, String> {
     //private String userName;
     private Integer age;
     private Date birthday;
+    @Column(isLogicDelete = true)
+    private Boolean isDelete;
 
 //    private Gender gender;
 //
@@ -70,6 +73,14 @@ public class Account extends BaseEntity<String, Long, String> {
         this.birthday = birthday;
     }
 
+    public Boolean getDelete() {
+        return isDelete;
+    }
+
+    public void setDelete(Boolean delete) {
+        isDelete = delete;
+    }
+
     @Override
     public String toString() {
         return "Account{" +
@@ -77,7 +88,8 @@ public class Account extends BaseEntity<String, Long, String> {
                 ", userName='" + userName + '\'' +
                 ", age=" + age +
                 ", birthday=" + birthday +
-                ", roles=" + roles +
+                ", isDelete=" + isDelete +
+//                ", roles=" + roles +
                 '}';
     }
 }

mybatis-flex-test/mybatis-flex-spring-boot-test/src/main/resources/application.yml

@@ -7,7 +7,7 @@ spring:
     #    driver-class-name: com.mysql.cj.jdbc.Driver
     url: jdbc:mysql://localhost:3306/flex_test
     username: root
-    password: 123456
+    password: 12345678
   #    driver-class-name:
   #  datasource:
   #    driver-class-name: org.h2.Driver

mybatis-flex-test/mybatis-flex-spring-boot-test/src/test/java/com/mybatisflex/test/mapper/AccountMapperTest.java

@@ -31,7 +31,6 @@ import java.util.Date;
 import java.util.List;
 
 import static com.mybatisflex.core.query.QueryMethods.column;
-import static com.mybatisflex.core.query.QueryMethods.concat;
 import static com.mybatisflex.test.model.table.AccountTableDef.ACCOUNT;
 import static com.mybatisflex.test.model.table.RoleTableDef.ROLE;
 import static com.mybatisflex.test.model.table.UserRoleTableDef.USER_ROLE;
@@ -48,6 +47,26 @@ class AccountMapperTest {
     @Autowired
     private AccountMapper accountMapper;
 
+    @Test
+    void testCount() {
+        QueryWrapper queryWrapper = QueryWrapper.create()
+                .select()
+                .from(ACCOUNT)
+                .groupBy(ACCOUNT.AGE);
+
+        long count = accountMapper.selectCountByQuery(queryWrapper);
+
+        Assertions.assertEquals(2, count);
+
+        queryWrapper = QueryWrapper.create()
+                .select(distinct(ACCOUNT.AGE))
+                .from(ACCOUNT);
+
+        count = accountMapper.selectCountByQuery(queryWrapper);
+
+        Assertions.assertEquals(2, count);
+    }
+
     @Test
     void testInsert() {
         Account account = new Account();