Constraints are part of a database schema definition. A constraint is usually associated with a table and is created with a CREATE CONSTRAINT or CREATE ASSERTION SQL statement. They define certain properties that data in a database must comply with. They can apply to a column, a whole table, more than one table or an entire schema. A reliable … Read more
This means the MySQL query did not execute correctly. You can use this to figure out what went wrong: although in this case it seems the problem is that you have not enclosed table and column names within the required ` marks, so try
Does this include: International numbers? Extensions? Other information besides the actual number (like “ask for bobby”)? If all of these are no, I would use a 10 char field and strip out all non-numeric data. If the first is a yes and the other two are no, I’d use two varchar(50) fields, one for the … Read more
Take a look at this. Change your query to: The last select is your count.
Create the hobby table similarly to this:
Cast/Convert the values to a Date type for your group by.
We have many databases in our MySQL and we want to shrink/purge ibdata1 file in MySQL. How can we drop all the databases from the MySQL except information_schema and mysqld databases?
I know this is an old question. The way I solved it – after failing by increasing the length or even changing to data type text – was creating an XLSX file and importing. It accurately detected the data type instead of setting all columns as varchar(50). Turns out nvarchar(255) for that column would have … Read more
Without an index, maintaining an autoincrement column becomes too expensive, that’s why MySQL requires an autoincrement column to be a leftmost part of an index. You should remove the autoincrement property before dropping the key: Note that you have a composite PRIMARY KEY which covers all three columns and id is not guaranteed to be … Read more
I use Node.js server side. I tried my code on localhost and everything works fine. I bought a server and installed Apache and node.js on it and test my web application there. I correctly changed the MySQL connection configurations from localhost to the server configurations. I test my web application with this configuration: I start … Read more