判断数据库里有没有要展示的表

来源：互联网发布：期货软件怎么用编辑：程序博客网时间：2024/04/30 01:57

当要展示的表按时间取时，即一天一张表或者一个月一张表时，需要在findPager()方法里判断是否存在要展示的这张表，如果不做判断而数据库里又没有这张表，会报404的错。
eg: 修改BaseTemplateDaoImpl.java中的findPager()方法

String querysql = "SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'itvsys' and TABLE_NAME='"+tableName+"'";        int tableCount = jdbcTemplate.queryForInt(querysql);        int totalCount = 0;        if(tableCount>0) {            totalCount = jdbcTemplate.queryForInt("select count(*) from " + tableName + where);            String order = "";            if (StringUtils.isNotEmpty(pager.getOrderBy()) && pager.getOrder() != null) {                order = " order by " + pager.getOrderBy() + " " + pager.getOrder();            }            String sql = "select * from " + tableName + where + order + " limit "                    + (pager.getPageNumber() - 1) * pager.getPageSize() + "," + pager.getPageSize();            // pager.setResult(jdbcTemplate.queryForList(sql));            pager.setResult(jdbcTemplate.query(sql, null, null, new RowMapper() {                @Override                public Object mapRow(ResultSet rs, int rowNum) throws SQLException {                    T t = null;                    try {                        t = entityClass.newInstance();                        Field[] fields = entityClass.getDeclaredFields();                        for (Field field : fields) {                            if (field.getName().equals("serialVersionUID")) {                                continue;                            }                            ReflectionUtil.setFieldValue(t, field.getName(), rs.getObject(field.getName()));                        }                    } catch (InstantiationException | IllegalAccessException e) {                        e.printStackTrace();                    }                    return t;                }            }));        }else {            try {                T t = entityClass.newInstance();            } catch (InstantiationException e) {                e.printStackTrace();            } catch (IllegalAccessException e) {                e.printStackTrace();            }            pager.setResult(new ArrayList<T>());        }

tips:
判断数据库里是否存在XX表的sql语句：

String querysql = "SELECT COUNT(*) FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'itvsys' and TABLE_NAME='"+tableName+"'";

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