.
When multiple group by columns exist, ROLLUP produces more complex results. At this time, each time a "break" appears in any column except the last classification column (value change), the inquiry will generate a high clustering cumulative row.
For example, in the absence of ROLLUP, a yearly, country, and product-based sales table list may be as follows:
01mysql> SELECT year, country, product, SUM(profit)02 -> FROM sales03 -> GROUP BY year, country, product;04+------+---------+----
://research.microsoft.com/en-us/groups/mlp/default.aspx(20) Research and study Forum; http://bbs.matwav.com/(21) Liuqingshan, assistant professor, Rutgers University, USA; http://www.research.rutgers.edu/~qsliu/(22) The latest information network of computer vision; http://www.cvchina.info/(23) test video download for motion detection, shadowing and tracking; http://apps.hi.baidu.com/share/detail/18903287(24) Prof. Xiaogang Wang, assistant professor o
, and product may be as follows:
Mysql> SELECT Year, country, product, SUM (profit)
-> from sales
-> GROUP by year, country, product;
+------+---------+------------+-------------+
| Year | Country | Product | SUM (Profit) |
+------+---------+------------+-------------+
| 2000 | Finland | Computer | 1500 |
| 2000 | Finland | Phone | 100 |
| 2000 | India | Calculator | 150 |
| 2000 | India | Computer | 1200 |
| 2000 | USA | Calcula
Vend_country. In addition, you need to enclose the vend_country in parentheses.In the SELECT statement in SQL, you can use a special operator to stitch together two columns.Depending on the DBMS you are using, this operator can be used with a plus (+) or two vertical bar (| | ) indicatesDescription: + with | |Access and SQL Sever use the + sign. Db2,orcale,postgresql,sqlite and open Office Base using | |Liezi:SELECT vend_name+_ ' (' +vend_country+ ') 'From vendorsORDER by Vend_name;Output:(No c
column (value change), the inquiry will generate a high clustering cumulative row.
For example, in the absence of ROLLUP, a yearly, country, and product-based sales table list may be as follows:
mysql> SELECT year, country, product, SUM(profit) -> FROM sales -> GROUP BY year, country, product;+------+---------+------------+-------------+| year | country | product | SUM(profit) |+------+---------+------------+-------------+| 2000 | Finland | Computer | 1500 || 2000 | Finla
USA Tom M 1970-09-02 USAUse the following command to load the text file "Mytable.txt" into the mytable table: mysql> load DATA LOCAL INFILE "Mytable.txt" intotable pet;Then use the following command to see if the data has been entered into the database table: mysql> select * FROM MyTable;In this article we learned how to create a database and database table and how to add records to a database table. So how do we retrieve data from a database table?1
See Http://my.chinaunix.net/xdkui in the textWhen it's okay, I like to play with Linux, but when I'm tired I want to have a rest. Linux under the less games, generally with wine or VMware installed Windows play win under the game. This article wants to say is the Linux under the MAME Simulator (http://www.mame.net/). Known as the most powerful multi-platform arcade simulator MAME supports a lot of arcade games. Advancemame and Xmame are very good mame port.began to install Advancemame (http://ad
whether the data has been input to the database table:Mysql> select * from mytable;In the previous article, we learned how to create a database and a database table, and how to add records to a database table.How can we retrieve data from database tables?1. Retrieve Information from a database tableIn fact, we have used the Select statement to retrieve information from database tables.The select statement format is generally:Select search keyword FROM the retrieved table Where search condition
://research.microsoft.com/en-us/groups/vc/(19) Shine ML and CV Study Group; http://research.microsoft.com/en-us/groups/mlp/default.aspx(20) Research and study Forum; http://bbs.matwav.com/(21) Liuqingshan, assistant professor, Rutgers University, USA; http://www.research.rutgers.edu/~qsliu/(22) The latest information network of computer vision; http://www.cvchina.info/(23) test video download for motion detection, shadowing and tracking; http://apps.h
. How to load delimitation data
1 data that is delimited by a particular character, may be enclosed in quotation marks, which is the most common data format for the current flat file.For bound data, the most commonly used format is comma-delimited value format. With this file format, each field in the data is separated by a comma from the next field. Text strings can be enclosed in quotes so that the string itself contains commas. If the string must also contain quotes, the general convention i
://research.microsoft.com/en-us/groups/vc/ (19) Shine ML and CV Study Group; http:// Research.microsoft.com/en-us/groups/mlp/default.aspx (20) Research and study Forum; http://bbs.matwav.com/(21) Liuqingshan, assistant professor, Rutgers University, USA; http://www.research.rutgers.edu/~qsliu/(22) The latest information network of computer vision; http://www.cvchina.info/(23) test video download for motion detection, shadowing and tracking; http://app
retrieved table Where the search condition (optional)The "*" used previously indicates that all columns are selected.The following continues with the table mytable we created in the previous article:2. Query all data:Mysql> select * FROM MyTable;+----------+------+------------+----------+| name | sex | Birth | birthaddr |+----------+------+------------+--------+| Abccs|f| 1977-07-07 | China || Mary |f| 1978-12-12 | USA || Tom |m| 1970-09-02 |
For mobile robots, keyboard control is often not enough to meet our needs, before watching a lot of movies inside are using a joystick to control the robot, is really handsome, just I have a joystick here, then to try to feel.
Operation Lever (joystick) control will be more operational, many of ROS in the robot also with the operation of the bar code, only a simple transplant can be. We are using a Saitek rod, as shown in the following illustration:
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