修复代码生成导入后必填项与数据库不匹配问题

@@ -40,7 +40,7 @@ PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     </select>
     </select>
 
 
     <select id="selectDbTableColumnsByName" parameterType="String" resultMap="GenTableColumnResult">
     <select id="selectDbTableColumnsByName" parameterType="String" resultMap="GenTableColumnResult">
-		select column_name, (case when (is_nullable = 'no' <![CDATA[ && ]]> column_key != 'PRI') then '1' else null end) as is_required, (case when column_key = 'PRI' then '1' else '0' end) as is_pk, ordinal_position as sort, column_comment, (case when extra = 'auto_increment' then '1' else '0' end) as is_increment, column_type
+		select column_name, (case when (is_nullable = 'no' <![CDATA[ && ]]> column_key != 'PRI') then '1' else '0' end) as is_required, (case when column_key = 'PRI' then '1' else '0' end) as is_pk, ordinal_position as sort, column_comment, (case when extra = 'auto_increment' then '1' else '0' end) as is_increment, column_type
 		from information_schema.columns where table_schema = (select database()) and table_name = (#{tableName})
 		from information_schema.columns where table_schema = (select database()) and table_name = (#{tableName})
 		order by ordinal_position
 		order by ordinal_position
 	</select>
 	</select>