- 博客(103)
- 资源 (3)
- 问答 (1)
- 收藏
- 关注
RSS订阅原创 Apache POI 之 初学实战篇 (三) --- 打开工作薄
可以通过加载文件的方式打开工作薄。对于XLS格式的文档直接创建File对象进行加载，对于XLSX格式的文档需创建InputStream对象进行加载。
2015-10-08 17:22:28
3949
1
原创 SQL基础（廿三）--- 数学函数
求绝对值：mysql> select fweight-50, abs(fweight-50), abs(-3.6) from t_person;+------------+-----------------+-----------+| fweight-50 | abs(fweight-50) | abs(-3.6) |+------------+-----------------+---
2015-02-10 16:52:43
524
原创 SQL基础（廿二）---UNION ALL
UNION与UNION ALL的区别：mysql> select * from t_employee;+----------+-------+------+---------+-------------+---------------+| fnumber | fname | fage | fsalary | fsubcompany | fdepartment |+---------
2015-02-10 15:44:44
835
原创 SQL基础（廿一）---UNION
UNION 规则：每个结果集必须有相同的列数；每个结果集的列必须类型相容。初始化条件：mysql> CREATE TABLE T_TempEmployee (FIdCardNumber VARCHAR(20),FName VARCHAR(20),FAgeINT ,PRIMARY KEY (FIdCardNumber)) -> ;Query OK, 0 row
2015-02-10 15:01:37
553
原创 SQL基础（廿）--- 抑制重复
查询每个员工的部门：mysql> select fdepartment from t_employee;+---------------+| fdepartment |+---------------+| Development || Development || HumanResource || HumanResource || InfoTech ||
2015-02-06 09:56:47
521
原创 SQL基础（一九）--- HAVING与LIMIT
查询各个年龄段人数大于1的年龄段：mysql> select fage,count(*) from t_employee -> group by fage -> having count(*)>1;+------+----------+| fage | count(*) |+------+----------+| 23 | 2 || 25 |
2015-02-05 16:51:24
2112
1
原创 SQL基础（一八）--- 数据分组与聚合函数
查询各个年龄段的人数：mysql> select fage, count(*) from t_employee -> group by fage;+------+----------+| fage | count(*) |+------+----------+| 22 | 1 || 23 | 2 || 25 | 2 |
2015-02-05 16:38:53
525
原创 SQL基础（一七）--- 数据分组
数据表信息:mysql> select * from t_employee;+----------+-------+------+---------+-------------+---------------+| fnumber | fname | fage | fsalary | fsubcompany | fdepartment |+----------+-------+---
2015-02-05 15:29:42
373
原创 SQL基础（一六）--- 范围值检测
查询年龄在23~27岁的员工信息：mysql> select * from t_employee -> where fage>=23 and fage<=27;+----------+-------+------+---------+| fnumber | fname | fage | fsalary |+----------+-------+------+---------+
2015-02-05 15:08:06
483
原创 SQL基础（一五）--- 多值检测
查询年龄是23、25、28的员工信息：方式一mysql> select * from t_employee -> where fage=23 or fage=25 or fage=28;+----------+-------+------+---------+| fnumber | fname | fage | fsalary |+----------+-------+----
2015-02-05 14:55:44
571
原创 SQL基础（一四）--- 反义运算符
查询年龄不等于22，并且工资不小于2000的员工信息：方式一mysql> select * from t_employee -> where fage=2000;+----------+-------+------+---------+| fnumber | fname | fage | fsalary |+----------+-------+------+---------
2015-02-05 14:48:12
1444
原创 SQL基础（一三）--- 空值检测
查询姓名为NULL的员工信息：错误查询：mysql> select * from t_employee -> where fname=null;Empty set正确查询：mysql> select * from t_employee -> where fname is null;+---------+-------+------+---------+| fn
2015-02-05 14:39:27
631
原创 SQL基础（一二）--- 匹配
单字符匹配：查询以‘erry’结尾的名称的员工信息：mysql> select * from t_employee -> where fname like '_erry';+----------+-------+------+---------+| fnumber | fname | fage | fsalary |+----------+-------+-----
2015-02-05 14:31:38
371
原创 SQL基础（一一）--排序
默认排序：mysql> select * from t_employee;+----------+-------+------+---------+| fnumber | fname | fage | fsalary |+----------+-------+------+---------+| DEV001 | Tom | 25 | 8300 || DEV002
2015-02-05 14:05:48
434
原创 SQL基础（一零）---Count
查询员工总数：mysql> select count(*), count(fnumber) from t_employee;+----------+----------------+| count(*) | count(fnumber) |+----------+----------------+| 8 | 8 |+----------+---
2015-02-05 13:55:24
969
原创 SQL基础（九）---聚合函数
查询年龄大于25岁的员工最高工资：mysql> select max(fsalary) from t_employee where fage>25;+--------------+| max(fsalary) |+--------------+| 6200 |+--------------+1 row in set查询工资大于3800元的员工平均年龄：mys
2015-02-05 11:50:30
385
原创 SQL基础（八）--SELECT
查询所有工资少于5000的员工姓名和工资：mysql> select fname,fsalary from t_employee where fsalary<5000;+-------+---------+| fname | fsalary |+-------+---------+| Jerry | 2300.8 || Jane | 2200.88 || Smith | 390
2015-02-05 11:41:47
390
原创 SQL基础（七）---SELECT
初始数据：mysql> create table t_employee( -> fnumber varchar(20), -> fname varchar(20), -> fage int, -> fsalary decimal(10,2), -> primary key(fnumber));Query OK, 0 rows affectedmys
2015-02-05 11:35:12
388
原创 SQL基础（六）- 删除
清空表数据：mysql> select * from t_person;+----------+------+---------+| fname | fage | fremark |+----------+------+---------+| Iurenl | 25 | BlaBla || Jim | 22 | BlaBla || Kimi
2015-02-05 10:59:36
436
原创 SQL基础(五)-update2
非空约束对数据更新的影响：mysql> update t_debt -> set famount=NULL -> where fperson='Tom';1048 - Column 'famount' cannot be nullmysql> update t_debt -> set famount=199.99 -> where fperson='Tom'
2015-02-05 10:20:46
413
原创 SQL基础(四)--update
将表t_person中所有人员的FREMARK字段值更新为“SuperMan”mysql> update t_person -> set fremark='SuperMan';Query OK, 7 rows affectedRows matched: 7 Changed: 7 Warnings: 0mysql> select * from t_person;+-----
2015-02-05 10:06:55
488
原创 SQL基础(三)
非空约束对数据插入的影响：mysql> insert into t_debt(fnumber,fperson) values('1','Jim');1364 - Field 'famount' doesn't have a default valuemysql> insert into t_debt(fnumber,famount,fperson) values('1',200,'Jim'
2015-02-05 09:49:30
503
安装Smart View for office错误
2015-03-24
TA创建的收藏夹 TA关注的收藏夹
TA关注的人