sqlc | type safe and fluent API | SQL Database library

You can do the following:

Your AJAX code is expecting an associative array with 3 keys: count, account_id, and name. You're not creating an associative array in the PHP code. You're just appending each account ID and name as separate array elements.

You can create and push onto separate arrays for the account IDs and names. Then put them in the associative array when creating the JSON at the end.

The simplest way, assuming you are using separate databases, is to maintain a map[tenantID]Repository, where tenantID is the way you differentiate between tenants (e.g. a string or uint that contains the tenant ID).

This way you can do everything at runtime:

• when you need to add a tenant, just instantiate the Repository for that tenant and add it to the map
• when you need to remove a tenant, just remove its Repository from the map and close the DB connection
• when you need to perform a query for a tenant, lookup the corresponding Repository in the map, and use it to perform the query for that tenant

If the operations above may happen concurrently, make sure that you're using some synchronization mechanism to avoid data races when accessing the map (e.g. sync.Map, or sync.RWMutex).

If you have a database table that stores the tenants and their DB connection URIs, you can still use this approach: when you need to perform a query check if the Repository exists in the map: if it's missing, query the tenant table and add the Repository for that tenant to the map. You can then periodically scan the map and remove any Repository that has not been used for some time.

To make all of this easier you could also wrap the whole machinery into a MultitenantRepository interface, that is identical to the Repository interface but that accepts an additional tenantID parameter on each method:

I am giving simple example assuming your code is from login.php

then you can edit as per your requirement.

#it is just a example how to show errors. Data sanitization, preventing sql injection etc is not considered in this example.

Your understanding is correct.

--files argument is uploading files to executors only.

See this in the spark documentation

file: - Absolute paths and file:/ URIs are served by the driver’s HTTP file server, and every executor pulls the file from the driver HTTP server.

You can read more about this at advanced-dependency-management

Now coming back to your second question

How can I upload to master?

There is a concept of bootstrap-action in EMR. From the official documentation it means the following:

You can use a bootstrap action to install additional software or customize the configuration of cluster instances. Bootstrap actions are scripts that run on cluster after Amazon EMR launches the instance using the Amazon Linux Amazon Machine Image (AMI). Bootstrap actions run before Amazon EMR installs the applications that you specify when you create the cluster and before cluster nodes begin processing data.

How do I use it in my case?

While spawning the cluster you can specify your script in BootstrapActions JSON Something like the following along with other custom configurations:

Do I understand correctly that the registration numbers in the database dò contain the hyphens ?

In that case, you should modify your query to hold wildcards (e.g. https://www.guru99.com/wildcards.html)

As for the case, either convert the case of the PHP variable before entering it in the query ( strtoupper(), strtolower() ), or try to solve your case in your table definition.

If the database entries do not hold the hyphens, you can filter them out the variable using a replace or preg_replace() to remove them.

Edit

if I assume your database holds very uniform inputs, like this :

The problem is that PHP doesn't know that it should only use the value of Model from the dropdown below the selected radio button. It uses the value of the last one. If the user leaves that one unselected, the value "" doesn't correspond to any of the ENUM values, so you get an error.

You can give them distinct names, and then select the appropriate one based on the radio button.

HTML:

A commit like "cdf7025: Add MySQL json test" (or "456fcb1 Add MySQL test for SELECT * JOIN") suggests joins are supported.

But it is true, as mentioned in issue 643, that queries with JOINs are for now not documented yet.

1. add a column base_folder that contains only the folder part without the file, that will be used for joinning
2. group by base_folder and calculate max timestamp
3. join with original dataframe using base_folder and get max timestamp for rows where it's null