MySQL - Read For Learn

What does SQL Select symbol || mean?

|| represents string concatenation. Unfortunately, string concatenation is not completely portable across all sql dialects: ansi sql: || (infix operator) mysql: concat ( vararg function ). caution: || means ‘logical or’ (It’s configurable, however; thanks to @hvd for pointing that out) oracle: || (infix operator), concat ( caution: function of arity 2 only ! ) postgres: || (infix operator) sql server: + (infix operator), concat ( vararg function ) sqlite: || (infix operator) hopefully the confusion is complete … Read more

How do I quickly rename a MySQL database (change schema name)?

For InnoDB, the following seems to work: create the new empty database, then rename each table in turn into the new database: You will need to adjust the permissions after that. For scripting in a shell, you can use either of the following: OR Notes: There is no space between the option -p and the password. If your … Read more

Your password does not satisfy the current policy requirements

Because of your password. You can see password validate configuration metrics using the following query in MySQL client: The output should be something like that : then you can set the password policy level lower, for example: Check the MySQL Documentation.

MySQL ERROR 1045 (28000): Access denied for user ‘bill’@’localhost’ (using password: YES)

You probably have an anonymous user ”@’localhost’ or ”@’127.0.0.1′. As per the manual: When multiple matches are possible, the server must determine which of them to use. It resolves this issue as follows: (…) When a client attempts to connect, the server looks through the rows [of table mysql.user] in sorted order. The server uses the first row that matches the … Read more

#1273 – Unknown collation: ‘utf8mb4_unicode_520_ci’

You can solve this by finding in your .sql file, and swapping it with

PHP Connection failed: SQLSTATE[HY000] [2002] Connection refused

I found the reason why the connection was not working, it was because the connection was trying to connect to port 8888, when it needed to connect to port 8889. This fixed the problem, although changing the server name to localhost still gives the error. Connection failed: SQLSTATE[HY000] [2002] No such file or directory But … Read more

How do I import an SQL file using the command line in MySQL?

Try: Check MySQL Options. Note 1: It is better to use the full path of the SQL file file.sql. Note 2: Use -R and –triggers to keep the routines and triggers of original database. They are not copied by default. Note 3 You may have to create the (empty) database from MySQL if it doesn’t exist already and the exported SQL don’t contain CREATE DATABASE (exported … Read more

Not unique table/alias

Your query contains columns which could be present with the same name in more than one table you are referencing, hence the not unique error. It’s best if you make the references explicit and/or use table aliases when joining. Try

Installation of MySQL for Visual Studio 1.2.8 failed

Today I’ve encountered a similar error. In my case I couldn’t uninstall mysql-visualstudio-plugin-1.1.1.msi. Also had MySQL Connector Net 6.7.4 + 6.8.3 installed before (and more stuff which give and gave me many errors to solve manually). Before doing machine.config replacement as described below, first make a backup or rename them, of course. Modified versions of … Read more

MySQL root password change

I found it! I forgot to hash the password when I changed it. I used this query to solve my problem: update user set password=PASSWORD(‘NEW PASSWORD’) where user=’root’; I forgot the PASSWORD(‘NEW PASSWORD’) and just put in the new password in plain text.

+ More