How to unblock with mysqladmin flush hosts

mysqladmin is not a SQL statement. It’s a little helper utility program you’ll find on your MySQL server… and “flush-hosts” is one of the things it can do. (“status” and “shutdown” are a couple of other things that come to mind). You type that command from a shell prompt. Alternately, from your query browser (such … Read more

SQL – IF EXISTS UPDATE ELSE INSERT INTO

What I’m trying to do is INSERT subscribers in my database, but IF EXISTS it should UPDATE the row, ELSE INSERT INTO a new row. Ofcourse I connect to the database first and GET the $name, $email and $birthday from the url string. This works, but just adds the new row; Here’s what I tried; … Read more

ROW_NUMBER() in MySQ

I want the row with the single highest col3 for each (col1, col2) pair. That’s a groupwise maximum, one of the most commonly-asked SQL questions (since it seems like it should be easy, but actually it kind of isn’t). I often plump for a null-self-join: “Get the rows in the table for which no other … Read more

MySQL Error 1215: Cannot add foreign key constraint

I’m guessing that Clients.Case_Number and/or Staff.Emp_ID are not exactly the same data type as Clients_has_Staff.Clients_Case_Number and Clients_has_Staff.Staff_Emp_ID. Perhaps the columns in the parent tables are INT UNSIGNED? They need to be exactly the same data type in both tables.

How to store arrays in MySQL?

The proper way to do this is to use multiple tables and JOIN them in your queries. For example: The person_fruit table contains one row for each fruit a person is associated with and effectively links the person and fruits tables together, I.E. When you want to retrieve a person and all of their fruit … Read more