When to use SELECT … FOR UPDATE?

The only portable way to achieve consistency between rooms and tags and making sure rooms are never returned after they had been deleted is locking them with SELECT FOR UPDATE. However in some systems locking is a side effect of concurrency control, and you achieve the same results without specifying FOR UPDATE explicitly. To solve this problem, Thread … Read more

#1055 – Expression of SELECT list is not in GROUP BY clause and contains nonaggregated column this is incompatible with sql_mode=only_full_group_by

I had a struggle getting this to work i’ve tested it and it’s working on lamp server mysql version 5.12 So, steps to success: sudo vim /etc/mysql/conf.d/mysql.cnf Scroll to the bottom of file Copy and paste[mysqld] sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION to the bottom of the file save and exit input mode sudo service mysql restart to restart MySQL. Done!

How to Select Top 100 rows in Oracle?

Assuming that create_time contains the time the order was created, and you want the 100 clients with the latest orders, you can: add the create_time in your innermost query order the results of your outer query by the create_time desc add an outermost query that filters the first 100 rows using ROWNUM Query: UPDATE for Oracle 12c … Read more

Why does NULL = NULL evaluate to false in SQL server

Think of the null as “unknown” in that case (or “does not exist”). In either of those cases, you can’t say that they are equal, because you don’t know the value of either of them. So, null=null evaluates to not true (false or null, depending on your system), because you don’t know the values to … Read more

Authentication plugin ‘caching_sha2_password’ cannot be loaded

You can change the encryption of the user’s password by altering the user with below Alter command : ALTER USER ‘username’@’ip_address’ IDENTIFIED WITH mysql_native_password BY ‘password’; OR We can avoid this error by make it work with old password plugin: First change the authentication plugin in my.cnf file for Linux / my.ini file in Windows: [mysqld] … Read more