Home PC Games Linux Windows Database Network Programming Server Mobile  
  Home \ Database \ MySQL function: group_concat () function     - Android Studio Installation and Configuration Guide tutorial (Linux)

- How to determine whether the Linux server was hacked (Linux)

- Defensive programming in PHP (Programming)

- Shell array: Define Shell array, the array length (Programming)

- Linux kernel likely and unlikely to resolve macro definitions (Linux)

- MySQL 5.7.10 source code for the latest version of the installation process in detail (Database)

- Depth understanding of JavaScript new mechanism (Programming)

- Introduction to thread pooling and simple implementation (Programming)

- httpd-2.4 feature (Server)

- Use the vi text editor and copy and paste Linux tips (Linux)

- Upgrading to Debian 7.6 glibc 2.15 (Linux)

- Nagios plugin installation tutorial of Nrpe (Linux)

- 17 How to install the Ubuntu 14.04 and Linux Mint Kodi14 (XBMC) (Linux)

- Linux Command Tutorial: cat command to view the contents of the file (Linux)

- How to modify the Linux NIC eth1 to eth0 (Linux)

- CentOS 6.4 dial-up Raiders (Linux)

- CentOS 6.4 (64bit) install Python 2.7.5 (Linux)

- Introduction Linux namespace (Linux)

- iOS persistence of data archiving NSKeyedArchiver (Programming)

- XP virtual machine under VirtualBox solve occupy 100% CPU problem (Linux)

  MySQL function: group_concat () function
  Add Date : 2018-11-21      
This function will merge non-null column values ​​in accordance with the grouping condition and eventually returned. If a null value is returned is empty, the complete syntax is as follows:
GROUP_CONCAT ([DISTINCT] expr [, expr ...]
            [ORDER BY {unsigned_integer | col_name | expr}
                [ASC | DESC] [, col_name ...]]
            [SEPARATOR str_val])
Example Column 1:
    SUM (VALUE1),
    SUM (VALUE2),
    SUM (VALUE3),

Column 2:

    SUM (VALUE1),
    SUM (VALUE2),
    SUM (VALUE3),

The above column 1 and column 2 the difference is that the column 2 is the field REAS_1, REAS_2, REAS_3 field one by one as a complete merger.
The maximum length of the receive function group_concat_max_len environment variables defined, it defaults to 1024, of course, can be set higher. At the same time the effective maximum length is returned by the max_allowed_packet constraints.
Group_concat_max_len running is to modify the following syntax:
SET [GLOBAL | SESSION] group_concat_max_len = val;

The result returned is a binary or non-binary character, depending on the value of the function within the field itself. Usually when group_concat_max_len < = 512, in order to VARCHAR or VARBINARY, when the value is greater than the TEXT and BLOB.
- Using iptables achieve NAT (Linux)
- How to compile and install wxWidgets in Ubuntu / Debian / Linux Mint (Linux)
- SUSE Linux firewall configuration notes (Linux)
- Installation under Linux to deploy Java (Linux)
- Internet proxy workaround can not be used under Linux YUM (Linux)
- Python format string (Programming)
- Four levels of intrusion on Linux server and counter-measures (Linux)
- Linux static library generated Guide (Programming)
- To create a problem by the statement date comparison of the difference between MySQL and Oracle (Database)
- CentOS6.3 build a Python 3.3 environment to access Oracle 11gR2 (Database)
- CentOS 6.4 Python 2.6 upgrade to 2.7 (Linux)
- Udev: Device Manager for Linux Fundamentals (Linux)
- Talk about the Linux ABI compatibility Application (Linux)
- UNIX file permissions in the "set user ID bit" (Linux)
- Use mysqldump backup performed MariaDB (Database)
- About Nginx 7 (Server)
- How to modify the Emacs Major Mode Shortcuts (Linux)
- Binary Tree Traversal (Linux)
- C language function pointer and a callback function (Programming)
- According to the national position on how to block traffic in Linux (Server)
  CopyRight 2002-2022 newfreesoft.com, All Rights Reserved.