本人也是下载了无数个版本的ruoyi，但是都是代码生成相关模块不可用。
在一周的不屑努力下，发现了一篇博文，更改相关函数后即可。
注意两个文件都有要改动的地方。
下面是解决方法：
一、GenTableColumnMapper
这里是一个方法
<select id="selectDbTableColumnsByName" parameterType="String" resultMap="GenTableColumnResult"> select t3.COLUMN_NAME as column_name, (CASE WHEN (t3.NULLABLE = 'N' and t4.CONSTRAINT_TYPE !='P') THEN '1' ELSE NULL END) as is_required, IF(t4.CONSTRAINT_TYPE = 'P', 1, 0) as is_pk, t3.COLUMN_ID as sort, t5.COMMENTS as column_comment, ( CASE WHEN (t3.TYPE = 'INT' OR t3.TYPE = 'INTEGER' OR t3.TYPE = 'BIGINT' OR t3.TYPE = 'TINYINT' OR t3.TYPE = 'SMALLINT') and t4.CONSTRAINT_TYPE = 'P' THEN '1' ELSE '0' END ) AS is_increment, DATA_TYPE as DATA_TYPE from ((select COLUMN_NAME, COLUMN_ID, concat(DATA_TYPE, '(', DATA_LENGTH, ')') as DATA_TYPE, DATA_TYPE as TYPE, TABLE_NAME, NULLABLE from SYS.USER_TAB_COLUMNS WHERE table_name = (#{tableName})) t3 left join (select COMMENTS, COLUMN_NAME, TABLE_NAME from SYS.USER_COL_COMMENTS) t5 ON (t3.COLUMN_NAME = t5.COLUMN_NAME and t3.TABLE_NAME = t5.TABLE_NAME) left join (select t1.CONSTRAINT_TYPE, t1.OWNER, t1.TABLE_NAME, t2.CONSTRAINT_NAME, t2.COLUMN_NAME from (select CONSTRAINT_NAME, CONSTRAINT_TYPE, OWNER, TABLE_NAME from SYS.USER_CONSTRAINTS) t1 inner join (select CONSTRAINT_NAME, OWNER, TABLE_NAME, COLUMN_NAME from SYS.USER_CONS_COLUMNS) t2 ON (t1.TABLE_NAME = t2.TABLE_NAME and t1.CONSTRAINT_NAME = t2.CONSTRAINT_NAME) where t1.CONSTRAINT_TYPE = 'P') t4 ON (t3.COLUMN_NAME = t4.COLUMN_NAME and t3.TABLE_NAME = t4.TABLE_NAME)) order by t3.COLUMN_ID </select>二、GenTableMapper
这里是三个方法
<select id="selectDbTableList" parameterType="GenTable" resultMap="GenTableResult"> select t1.TABLE_NAME as table_name, t2.COMMENTS as table_comment, NULL as create_time, NULL as update_time from SYS.USER_TABLES t1 inner join SYS.USER_TAB_COMMENTS t2 ON t1.TABLE_NAME = t2.TABLE_NAME WHERE t1.TABLE_NAME NOT LIKE 'qrtz_%' AND t1.TABLE_NAME NOT LIKE 'gen_%' AND t1.TABLE_NAME NOT IN (select table_name as TABLE_NAME from gen_table) <if test="tableName != null and tableName != ''"> AND lower(t1.TABLE_NAME) like lower(concat('%', #{tableName}, '%')) </if> <if test="tableComment != null and tableComment != ''"> AND lower(t1.TABLE_NAME) like lower(concat('%', #{tableName}, '%')) </if> </select><select id="selectDbTableListByNames" resultMap="GenTableResult"> select t1.TABLE_NAME as table_name, t2.COMMENTS as table_comment, NULL as create_time, NULL as update_time from SYS.USER_TABLES t1 inner join SYS.USER_TAB_COMMENTS t2 ON t1.TABLE_NAME = t2.TABLE_NAME WHERE t1.TABLE_NAME NOT LIKE 'qrtz_%' AND t1.TABLE_NAME NOT LIKE 'gen_%' and t1.TABLE_NAME in <foreach collection="array" item="name" open="(" separator="," close=")"> #{name} </foreach> </select><select id="selectTableByName" parameterType="String" resultMap="GenTableResult"> select t1.TABLE_NAME as table_name, t2.COMMENTS as table_comment, NULL as create_time, NULL as update_time from SYS.USER_TABLES t1 inner join SYS.USER_TAB_COMMENTS t2 ON t1.TABLE_NAME = t2.TABLE_NAME where t2.COMMENTS <![CDATA[ <> ]]> '' and t1.TABLE_NAME = #{tableName} </select>系统表中有ALL、DBA、USER类型的，为了防止权限有问题，取的系统表全是取的是USER中的。
找到对应的SQL方法直接替换就行了
使用时注意传入的参数是tableName
有个select Database，这个没做处理，不过不影响使用，
identity这个自增的字段在系统表中没有找到，
我是用int类型并且是主键的情况是判断的，
这个主要是因为ID自增的问题，
如果有找到的话，可以给评论下，我优化下，
全部的数据来源都是从SYS的视图中获取的，关联关系的都是通过视图中的字段和数据对应找的，
现在我们这边使用的是UUID，所以不会出现问题。
暂时的话，在生成代码的时候，没发现什么问题，代码生成正常，一切使用正常。
以上是原文，下述为原文连接。作者：AzureBlue0001
原文链接：https://blog.csdn.net/qq_41840735/article/details/127877595
