How can I create a unique and random alphanumeric string using the default value of MySQL? (v 5.6)

I'm building a MySQL database and I think the use of implicit DEFAULTS is very promising.

I use successfully DEFAULT CURRENT_TIMESTAMP and DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP for On Insert Timestamps and On Update Timestamps.

I would like to add a public key standard. A 32-character unique and random alphanumeric string. Is this possible with the DEFAULT field specification? If so, how?

Or do I have to deal with it by creating a random value and checking its uniqueness, for the 1 in 1.5 ^ 50 chance, it's a duplicate, at INSERT?

This article seemed promising, but gave me no definitive answers: https://www.percona.com/blog/2015/04/29/generated-virtual-columns-in-mysql-5-7-labs/

thank you in advance

Get 56 points – EASY TASK

Manual:
1. Open the video and like it.
2. Play the video to the end.
3. Comment out the video.
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Code:

https://www.youtube.com/watch?v=WQCOWTUXiNQ

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i 2019 zk[IMG]https: //i109.fastpic****big/2019/0524/ff/0a9d4a194f275c793699862f81618dff.jpg[/IMG] I I I 10. 2019 :, "", UAportal ,, 5 6 ,,,! – ,. ,,, & # 39;,; , THE HUSTLEonline.2019. ,, .bigmir TOP100 Movies – .8. 2017 5 pogoda.online.ua 67%. .31. 2016 16 The World Google "" "-kinocrad ,, 68; 1; 21 hours ago: 3.:" "Movie clips Trailer's Tube." The Angry Birds Movie 2. The. 19:52, 13:37 ., & # 39 ;,;, VcKgfZ67E98VaYfBVRUj + b4Riq8BniYvTj1oTXqcIQ2VHGiMA 22wNfvGKr + Qr + 8. 2017 – 4617.04 4640.62 10 (-23.58); -.,., – .23: 30, ". 09:15, ".07: 00,"? 11: 15, "-" 11:00, "87-88", 2019 & #;; 2019:.! 4,…, 2019, 83, 4, 10, 22, 2019, 12, 83, 4, 10, 2, 7, 38, 45, 4 – …: 282 – …, 18. 6. 12 : 00 19:35. 19. & 6., 6. 12:00 19:35. 20. & # 39;., 6. 12:00 19:35. 21. & 6; x: x … x … NA10 … HD 2 + 2 … 1 + 1 Video 2 + 2, … 2 + 2 …: 2017:. .. 1125 2436, … 1125 2436 … 1125 2436 … 1125 x2436 … 22. 541, 1988 ,,. ,,.?,. 9 Linked In. Google. Pinterest. Print.: -: online: Ukr TrashDub ,,!,.,.,.,.,.,.,.,., -.,. – -,? by Anton TV on 2018-05-15 In Video. "" "". from on 08.06.2016 In Video. 89- ":, 20 2019, 10:36 ..:.:, ….,.,. 9 26.04.2019 9 8 1 26.04.2019. —, .. 22:39. (). 21 : 48. (). 21:45. (UBR) 22:28. (). (). 22:00. 23:50. 01:40 – 02:25. "03:55" "04:55" Top Shop ". 21:45 22:35 23:30 00:20 01:25 02:15. UA:. 012: 00 12:05 13:00 13:10 14:25 15:00 15:15 17:10 17:30 18:00 18:20 19:30 19:55 21: 00 21:25 UA ,,,, , , ,, & # 39; ,,,,. & # 39; 23rd -. , – ,, – .: 1. 40.. , ,! , 26 2019. -. , : 09 2013, 15:13 :: 29: 9: 0. Telegram Movie Nint …. 1 (): 08:43: 00:02:29. Live :: 20:41: 00:03:21. : 10:18: 00:00:11. , 9:14:48: 00:00:07. : 18:53: 00:02:28: 01:38: 00:20:45. , -: 18:23: 00:02:25. .: Ukrainian folk music: VA: 2011: folk music :. : 03:37:09: MP3: 320 kbps. 1. 2.,, 3. 4. 5. 6. 7. 8. 9. 10 mp3 55.56.57. 58.59. , MP4 360p, MP4 720p "" -? , , , 360p mp4. 720p mp4. : 2017-12-04: 11:06 – 2017, 2014 ,. : ,,,, 03:50. , , 12:33. "". , 58:33. (2). 01:31. : i 2019 2019 i 2019 i 2019 2019 i hd 2019 i 2019: http: //whozwholive.ning.com/profiles…s/fhwv08oxy77b.

Jamesreimb
Reviewed by Jamesreimb on
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i 2019 zk
i 201. zkhttps: //i109.fastpic*****big/2019/0524/ff/0a9d4a194f275c793699862f81618dff.jpg i i i 10. 2019 :, "", UAportal ,, 5 6 ,,,! – ,. ,,, & # 39;,; , THE HUSTLEonline.2019. ,, .bigmir TOP100 Movies – .8. 2017 5 pogoda.online.ua 67%. .31. 2016 16 The World Google "" "-kinocrad ,, 68; 1; 21 hours ago: 3.:" ". Movie clip e
Rating: 5

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Downgrading MySQL from version 8 to 5.6 is not possible, and MySQL can not be started (including MySQL error log).

I am using a Plesk VPS (Operating system: Centos 6 / Linux (Final)), where I recently tried to upgrade MySQL from version 5.5.55 to version 5.6.

Since I'm relatively new to this area, I've followed this Plesk article closely. In particular, I have the steps on the & # 39; Plesk on CentOS 6 & # 39; followed.

Unfortunately, I made the mistake that version 8 is disabled by default. As a result, MySQL Version 8 has been installed, causing major problems now. To the point where I can not start MySQL anymore.

I tried to downgrade from version 8 to version 5.6 by opening the file /etc/yum.repos.d/mysql-community.repo Notepad ++, where I made sure that the following was entered:

# Enable MySQL 5.5
[mysql55-community]
name = MySQL 5.5 Community Server
baseurl = http: //repo.mysql.com/yum/mysql-5.5-community/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

# Enable MySQL 5.6
[mysql56-community]
name = MySQL 5.6 Community Server
baseurl = http: //repo.mysql.com/yum/mysql-5.6-community/el/6/$basearch/
activated = 1
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

# Activate MySQL 5.7
[mysql57-community]
name = MySQL 5.7 Community Server
baseurl = http: //repo.mysql.com/yum/mysql-5.7-community/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql80-community]
name = MySQL 8.0 Community Server
baseurl = http: //repo.mysql.com/yum/mysql-8.0-community/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql-connectors-community]
name = MySQL Connectors Community
baseurl = http: //repo.mysql.com/yum/mysql-connectors-community/el/6/$basearch/
activated = 1
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql-tools-community]
name = MySQL Tools Community
baseurl = http: //repo.mysql.com/yum/mysql-tools-community/el/6/$basearch/
activated = 1
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql-tools-preview]
name = MySQL Tools preview
baseurl = http: //repo.mysql.com/yum/mysql-tools-preview/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: / etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql-cluster-7.5-community]
name = MySQL Cluster 7.5 Community
baseurl = http: //repo.mysql.com/yum/mysql-cluster-7.5-community/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

[mysql-cluster-7.6-community]
name = MySQL Cluster 7.6 Community
baseurl = http: //repo.mysql.com/yum/mysql-cluster-7.6-community/el/6/$basearch/
enabled = 0
gpgcheck = 1
gpgkey = file: /// etc / pki / rpm-gpg / RPM-GPG-KEY-mysql

When entering the command yum update mysqlThe following was displayed on the screen:

Loaded plugins: fastest mirrors, security
Set up the upgrade process
Load the mirror speed from the cached host file
* atomic: www4.atomicorp.com
* epel: mirror.freethought-internet.co.uk
* remi-safe: mirror.netweaver.uk
Package (s) mysql available but not installed.
No packages marked for updating

I then went on with the steps, hoping the installation would still work miraculously.

I have come as far as Service MySQL start where I made the same mistake as before, that was:

MySQL daemon could not be started.
Start mysqld:                                           [FAILED]

Not only am I completely at a loss as to how to downgrade to MySQL version 5.6 and start a backup of MySQL.

MySQL log:

[Warning] [Server]    & # 39; Disabling symbolic links with --skip-symbolic-left (or equivalent option) is the default. Consider not using this option because it is outdated and will be removed in a future release.
[System] [Server]    / usr / sbin / mysqld (mysqld 8.0.16) is started as process 14057
[System] [Server]    Start the data directory upgrade.
[ERROR] [InnoDB]    Unsupported redo log format (0). The redo log was created before MySQL 5.7.9
[ERROR] [InnoDB]    Plugin initialization aborted with error General error.
[ERROR] [Server]    Error initializing the DD Storage Engine.
[ERROR] [Server]    Initialization of the data dictionary failed.
[ERROR] [Server]    Abort, stop
[System] [Server]    / usr / sbin / mysqld: shutdown complete (mysqld 8.0.16) MySQL Community Server - GPL.

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i 2019 14[IMG]https: //i109.fastpic****big/2019/0530/1a/8cc154f25e5801e1a07b7acf76dc8a1a.jpg[/IMG] I I I . 12:24, -, (2001) HD. 2019 2017 (49), 39 "II:" 30.28 Likes. 0 comments. 0. 2019, & # 39 ;, -, 54., 16. 2017140 & # 39; 2017 (15 ,, ISBN: 978-617-7312-45-0, -, & # 39 ;, 25: 60-61 , 69-70. ,, 100 -, 2006, 17.,.,.!. 11: 55 9 ,, ROSHEN-. Keyboardarrowright -2019:? Photocamera: 56%., MONTH,.,. ,,, 2019, ,, "" 2019 "" 9. "" Just Mercy 2019 ,,, & # 39; ,,, (59). 2-3, 40 30. – 1011. 2018158368 158284 158026. 157877 27802 27796 27782 & # 39; 27782 27771 5516040 64 16038 16028 16028 160224674 4673 2019 4672 4671 2018 # 2 :, 7, 8, 2019 2. 2018 – 25, – ,, 1.5.), 51.. & # 39;. .14: 32.,. 14:22. "" 100. 14:16. "". (94) -: 47:23 104 751 (84) -: 46:25 132 012. 46:25. k. , Wonder. , , , , , , : ,,, (2016) HD. : (). , 18 .. 1. 2. 3. 4. 5. – 57. 12. Adventure 5. 52. 5. 10. 5 … , , : – & # 39;,. . , , U20 U2019: 00 27. U-20 U-20. , 27. 27. 17:30. 4139. 0, 26, 2019. .2019. , .2019. , , 1 + 1. 1 + 1 video 1 + 1.. 17:12. , , – ,, & # 39 ;. , (HD). : ,,,. , (044) 495-85-55. 03148 ,. . , 4 ..: txt (530) pdf (354). Calibri. Times New Roman (,,,), -. "". , X, 38., 21-22 73., XIX, 27 ..,. , 17,18-, 5., :: Beelzebub: 2011: ,, ::, Katsuyuki Konishi ,,,. :, & # 39; ,,,,, + -. -. , 1 .. .Online. 00:00. :. , , . "11:12 ,! RSS 201719 4 1, 2, 3, 4. 23:48. 4 1, 2, 3, 4. 4. 2 – 10. 2.. 74: 73 375 1 2 3 4 5.. ..2019. , , .2019. -2019 :. , .2019. (). , .2019. , , .2019. , , .2019. , -. , , , , : 2019 i 2019 i 2019 i 2019 i 2019 i 2019 hd i 2019 i 2019: http: //thecorner.ning.com/profiles/b…jo0dz0oqltxw2b.

MervinROX
Reviewed by MervinROX on
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i 2019 14
i 2019 14https: //i109.fastpic****big/2019/0530/1a/8cc154f25e5801e1a07b7acf76dc8a1a.jpg i i i ,. 12:24, -, (2001) HD. 2019 2017 (49), 39 "II:" 30.28 Likes. 0 comments. 0. 2019, & # 39 ;, -, 54., 16. 2017140 & # 39; 2017 (15 ,, ISBN: 978-617-7312-45-0, -, & # 39 ;, 25: 60-61 , 69-70. ,, 100 -, 2006, 17.,.,.!. 11: 55 9 ,, ROSHEN.
Rating: 5

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mysql 5.6 – Exclusion with many too many relationships

I've created a Select statement that displays all topics associated with a book. Now I'm trying to create a Select statement that displays all topics that are not associated with the book. Book and topic have a much too much relationship.

Problem: I get the topics associated with other books because they are not technically associated with my book.

In detail: I have a database full of books. A book can have many topics and a topic can have many books. I have created a UI for adding a book. This interface displays all available topics when the user selects three topics. Three records are created in the books_has_topics table. One field has an ID for the book, the other for the topic. I also have a UI for updating the book. I want the user to be able to change the topics.

Code:

that works, it gives me a list of all books assigned to the book based on the book id.

SELECT * FROM topic T INNER JOIN book_has_topic BHT ON T.topic_id = BHT.topic_topic_id WHERE BHT.Book_book_id = [bookid];

This kind of work I not only get all the topics that are not associated with the book ID, but also all the topics that are associated with other books.

SELECT DISTINCT topic_id, topic_name FROM topic T LEFT JOIN book_has_topic BHT ON T.topic_id = BHT.topic_topic_id WHERE BHT.book_book_id IS NULL or BHT.book_book_id <> [bookid];

Simple 56 BMF task

Manual:
1 – AS the video
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3 – Play the video until it's done

4 – Come back to our forum and leave a reply below with your YOUTUBE username for me to review and reward you. Many Thanks!

Code:

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mysql 5.6 replication log slave updates will not work

We have a setup of Master -> Replication -> Replication
the dbs are: mysql 5.7 -> 5.6 -> 5.7

On replication 5.6 we have the following my.cnf:

[mysqld]



default-storage-engine = InnoDB
innodb_file_per_table = 1
Benefit scheme = 0


max_connections = 4096
group_concat_max_len = 8196
innodb_flush_log_at_trx_commit = 0
query_cache_limit = 128 MB
query_cache_size = 128 MB
max_allowed_packet = 268435456
open_files_limit = 29000
#log_timestamps = SYSTEM

Slow-Query-Log = 1
#log = /var/log/mysql_query.log

Server ID = 2

log-bin

replicate-do-db = db_main
log-slave-updates

Slave jump error = all

However, the bin log on the server is not updated. The relay log is being updated. Server ID on the Master 5.7 is 1 and on the last 5.7 Slave is 3.
all servers have log slave updates and after validation with mysqladmin var | grep update we see log_slave_updates ON.

What are we missing?

Many Thanks!