To find all socket files on your system run: My Mysql server system had the socket open at /var/lib/mysql/mysql.sock Once you find where the socket is being opened, add or edit the line to your /etc/my.cnf file with the path to the socket file: Sometimes the system startup script that launched the command line executable specifies … Read more
I have set up PHP, MySQL, and Apache. localhost() for PHP and it is working well. But after I downloaded MySQL, it reports: Fatal error: Call to undefined function mysql_connect() How can I fix this?
You need to consider that GROUP BY happens after the WHERE clause conditions have been evaluated. And the WHERE clause always considers only one row, meaning that in your query, the meta_key conditions will always prevent any records from being selected, since one column cannot have multiple values for one row. And what about the redundant meta_value checks? If a value is allowed to … Read more
So, you have a com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failurejava.net.ConnectException: Connection refused I’m quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial: If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn’t reachable at all. This can have one or more of the following causes: IP … Read more
You don’t have full joins in MySQL, but you can sure emulate them. For a code sample transcribed from this Stack Overflow question you have: With two tables t1, t2: The query above works for special cases where a full outer join operation would not produce any duplicate rows. The query above depends on the UNION set operator to remove duplicate rows introduced by the query pattern. … Read more
For MySQL 5.0.3 and higher, you can use BIT. The manual says: As of MySQL 5.0.3, the BIT data type is used to store bit-field values. A type of BIT(M) enables storage of M-bit values. M can range from 1 to 64. Otherwise, according to the MySQL manual you can use BOOL or BOOLEAN, which are at the moment … Read more
It may be easier to check if the connection and re-establish it if needed. See PHP:mysqli_ping for info on that.
To find all socket files on your system run: My Mysql server system had the socket open at /var/lib/mysql/mysql.sock Once you find where the socket is being opened, add or edit the line to your /etc/my.cnf file with the path to the socket file: Sometimes the system startup script that launched the command line executable specifies … Read more
I have set up PHP, MySQL, and Apache. localhost() for PHP and it is working well. But after I downloaded MySQL, it reports: Fatal error: Call to undefined function mysql_connect() How can I fix this?
So, you have a com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failurejava.net.ConnectException: Connection refused I’m quoting from this answer which also contains a step-by-step MySQL+JDBC tutorial: If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn’t reachable at all. This can have one or more of the following causes: IP … Read more