优化：优化 SQL 语句风格

1.MySQL数据库>SQL语句>第10条：
【推荐】SQL 语句中表的别名前加 as，并且以 t1、t2、t3、...的顺序依次命名。
说明：
  1）别名可以是表的简称，或者是依照表在 SQL 语句中出现的顺序，以 t1、t2、t3 的方式命名。
  2）别名前加 as 使别名更容易识别。
正例：select t1.name from first_table as t1 , second_table as t2 where t1.id = t2.id
个人理解：使用 t1、t2、t3... 的表别名命名方式，在很多类似业务查询的场景会更方便复用；使用 AS 而不是 as 更容易阅读。

continew-admin-system/src/main/resources/mapper/MenuMapper.xml

@@ -2,27 +2,27 @@
 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
 <mapper namespace="top.charles7c.cnadmin.system.mapper.MenuMapper">
     <select id="selectPermissionByUserId" resultType="java.lang.String">
-        SELECT DISTINCT m.`permission`
-        FROM `sys_menu` as m
-            LEFT JOIN `sys_role_menu` as rm ON rm.`menu_id` = m.`id`
-            LEFT JOIN `sys_role` as r ON r.`id` = rm.`role_id`
-            LEFT JOIN `sys_user_role` as sur ON sur.`role_id` = r.`id`
-            LEFT JOIN `sys_user` as u ON u.`id` = sur.`user_id`
-        WHERE u.`id` = #{userId}
-          AND m.`type` IN (2, 3)
-          AND m.`status` = 1
-          AND r.`status` = 1
+        SELECT DISTINCT t1.`permission`
+        FROM `sys_menu` AS t1
+            LEFT JOIN `sys_role_menu` AS t2 ON t2.`menu_id` = t1.`id`
+            LEFT JOIN `sys_role` AS t3 ON t3.`id` = t2.`role_id`
+            LEFT JOIN `sys_user_role` AS t4 ON t4.`role_id` = t3.`id`
+            LEFT JOIN `sys_user` AS t5 ON t5.`id` = t4.`user_id`
+        WHERE t5.`id` = #{userId}
+          AND t1.`type` IN (2, 3)
+          AND t1.`status` = 1
+          AND t3.`status` = 1
     </select>
 
     <select id="selectListByUserId" resultType="top.charles7c.cnadmin.system.model.entity.MenuDO">
-        SELECT m.*
-        FROM `sys_menu` as m
-            LEFT JOIN `sys_role_menu` as rm ON rm.`menu_id` = m.`id`
-            LEFT JOIN `sys_role` as r ON r.`id` = rm.`role_id`
-            LEFT JOIN `sys_user_role` as sur ON sur.`role_id` = r.`id`
-            LEFT JOIN `sys_user` as u ON u.`id` = sur.`user_id`
-        WHERE u.`id` = #{userId}
-          AND m.`status` = 1
-          AND r.`status` = 1
+        SELECT t1.*
+        FROM `sys_menu` AS t1
+            LEFT JOIN `sys_role_menu` AS t2 ON t2.`menu_id` = t1.`id`
+            LEFT JOIN `sys_role` AS t3 ON t3.`id` = t2.`role_id`
+            LEFT JOIN `sys_user_role` AS t4 ON t4.`role_id` = t3.`id`
+            LEFT JOIN `sys_user` AS t5 ON t5.`id` = t4.`user_id`
+        WHERE t5.`id` = #{userId}
+          AND t1.`status` = 1
+          AND t3.`status` = 1
     </select>
 </mapper>

continew-admin-system/src/main/resources/mapper/RoleMenuMapper.xml

@@ -2,14 +2,11 @@
 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
 <mapper namespace="top.charles7c.cnadmin.system.mapper.RoleMenuMapper">
     <select id="selectMenuIdByRoleIds" resultType="java.lang.Long">
-        SELECT
-            `menu_id`
+        SELECT `menu_id`
         FROM `sys_role_menu`
-        <where>
-            `role_id` IN
-            <foreach collection="list" item="roleId" open="(" close=")" separator=",">
-                #{roleId}
-            </foreach>
-        </where>
+        WHERE `role_id` IN
+        <foreach collection="list" item="roleId" open="(" close=")" separator=",">
+            #{roleId}
+        </foreach>
     </select>
 </mapper>