auto-increment | Automaticly Increment properties

I have more than 10 million rows. Counting the number of rows is too slow. I want to estimate the number of rows.

Current query is like this:

In my Laravel 8 project I have a model called Campaign, my front-end though is build in Vue JS so needs to have some keys on a Campaign for contextual purposes, such as opening and closing a dropdown menu when looping over the elements, a database column isn't nessecery for this.

I'd like to add some default key/value pairs to my Campaign model, for example: dropdown_is_open and should have a default value of false.

I came across the default attributes for a model and tried adding this but cannot see my new key on the object, what am I missing?

An entity which has ID but the data in corresponding table was added manually, for this reason @GeneratedValue annotation was never added. Now I need to create records in this table through code and want my ID to be auto-incremented. On adding @Id @GeneratedValue(strategy = GenerationType.AUTO) Integer id; The exception I get is:

I have an MySQL table (MySQL 5.7) with the following columns: id (key), email, percentage, file_name. The table logs when students (identified by email) complete certain activities.

I need to return a list that has a row for each file_name that the student has completed. If they have completed a file_name more than once I want to return the most recent attempt, based on the auto-incrementing id. I've used a few answers on here to create the following query. The file_name string matches are to isolate particular activity types and levels:

I have a table as follows:

I would like to add a UNIQUE KEY on (connection_id, parent_container_id, name). However, parent_container_id and connection_id are a disjoin union -- the record must have one or the other. Because of this, I thought perhaps using the value 1 as the 'null' value (that is, the first entry when using an auto-incrementing ID) and creating a BASE entry in the container table for the 1 record.

Example data that I want to enforce uniqueness on:

• (connection_id=1, parent_container=null, name="hello")

• (connection_id=1, parent_container=null, name="hello") # should fail

• (connection_id=null, parent_container=10, name="goodbye")

• (connection_id=null, parent_container=10, name="goodbye") # should fail

Is this a poor approach to use or does this seem like a good way to enforce the Unique-ness constraint here? If it's not a good way, what might be a better way?

Update: my current solution is now using a generated (virtual) column with an md5 hash:

I need to create a cloudformation template for my dynamodb, but I need one of the indexes to be incremented automatically. CloudFormation template looks like this:

I am working on a use case where I need to implement a surrogate key. I have a column ID that should auto-increment by 1 but when I use merge it skips the 2 to 4 sequence.

I am new to DRF, so apologies if it's a trivial question.

I want to create an API endpoint to auto-increment the value of a column in the database, whenever a specified URL is hit.

For instance:

In the models.py file I have:

I have a table with a column that should auto-increment, however it should increment over another descriminator column

for example:

So if I would enter another entry with Descriminator "A" I would get Filenumber 3. But by adding an entry with "B", i would get 2, because it's the 2nd "B" Row.

The only way I know is a Update-Trigger but is there an easier solution or if it's the only way, is it reliable with heavy traffic (load-balanced system with many users)?