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Best way to create schemas in SQL

i would like to ask for help with my backend flux.
I'm starting to use SQL now, and i have some background in noSQL databases, but i don't know SQL much, so i'm having some trouble finding out how to register my schemas.
I'm using node-mysql, and the way that i can create schemas is calling the method query, like:
myInstance.query( 'CREATE TABLE users (
id INT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(100) NULL NULL,
email VARCHAR(100) NULL NULL,
password VARCHAR(100) NULL NULL
)');
The problem with this solution is: this code will run in every server initialization.
So, i would like to know how to check if the schema already exists, and.. is this a good solution?? I was thinking in a bash script that creates all schemas, them i don't need this if statements.
Thanks.

What you are calling a "schema" is really a "table". Hence, create table statement, rather than create schema. This is very important. Perhaps this part of the documentation will help you understand the difference.
There are four very different constructs:
Database Server -- how you connect to one or more databases
Database Instance -- a grouping of objects, typically a unit of backup and storage
Schemas -- a grouping of objects (which may be within a database), typically a unit of permissions
Tables -- where data is stored
Note that different database systems have slightly different variations on these.
Of course, "tables" have schemas, which is why it is easy to get confused.
Generally, the management of the database is handled separately from user applications. That is, the DBA (which might also be the developer) would create the database, manage access, handle backup/recovery, and other things. The application would simply connect to the database and assume that the correct tables and data are there.
That is, under most circumstances, you wouldn't be creating tables in application code. Just use the tables that should already have been created for your database.

You can modify you sql statement to
CREATE TABLE IF NOT EXISTS users (…
That way the code will run on server init, but not do anything and also not fail when the tables are already there. See the corresponding mysql documentation.
Contrary to the answer you got, to have the SQL statements in application code is not that uncommon for backends.

Backendless : Relationship between tables issue and advice

Good evening,
I currently have 3 tables on my API at backendless.
**Users** (objectId, email, username, password)
**figures** (objectId, figure_name, figure_cat, figure_image, figure_info)
My figures data has rows kind of like a product.
Basically, I would like to link entries in the figures table to users but i'm not sure the best way to go about it.
I can create relationships of one-to-one and one-to-many but being new to that i'm not sure the best way to go about it.
Any help or advice would be much appreciated :)

does a user have many figures?
Can multiple users share the same Figure?
Assuming that a user has many figures, so you will have a userid column in the figures table (1:M rel between user->figures). I also assume your figure_cat is a relatively static list, so consider a lookup table for that so it has a fkey in the figures table as well. Also depending on the size of images, it may be better to put images in a different table so you can put them in a different file group.
Assuming figures are shared by users, you may need a M:N table in between users and figures that stores the userid, to figureid mapping (sometimes called a "tie table" I think)
What database are you using?

You can create a relationship between the tables either directly in the console or by making an API call where you save an object which references other (related) objects. See the documentation for details: http://backendless.com/documentation/data/js/data_relations.htm

which is better, searching in javascript or database?

I have a grid(employee grid) which has say 1000-2000 rows.
I display employee name and department in the grid.
When I get data for the grid, I get other detail for the employee too(Date of Birth, location,role,etc)
So the user has option to edit the employee details. when he clicks edit, I need to display other employee details in the pop up. since I have stored all the data in JavaScript, I search for the particular id and display all the details. so the code will be like
function getUserDetails(employeeId){
//i store all the employeedetails in a variable employeeInformation while getting //data for the grid.
for(var i=0;i<employeeInformation.length;i++){
if(employeeInformation[i].employeeID==employeeId){
//display employee details.
}
}
}
the second solution will be like pass employeeid to the database and get all the information for the employee. The code will be like
function getUserDetails(employeeId){
//make an ajax call to the controller which will call a procedure in the database
// to get the employee details
//then display employee details
}
So, which solution do you think will be optimal when I am handling 1000-2000 records.
I don't want to make the JavaScript heavy by storing a lot of data in the page.
UPDATED:
so one of my friend came up with a simple solution.
I am storing 4 columns for 500 rows(average). So I don't think there should not be rapid slowness in the webpage.
while loading the rows to the grid, under edit link, I give the data-rowId as an attribute so that it will be easy to retrieve the data.
say I store all the employee information in a variable called employeeInfo.
when someone clicks the edit link.. $(this).attr('data-rowId') will give the rowId and employeeInfo[$(this).attr('data-rowId')] should give all the information about the employee.
instead of storing the employeeid and looping over the employee table to find the matching employeeid, the rowid should do the trick. this is very simple. but did not strike me.

I would suggest you make an AJAX call to the controller. Because of two main reasons
It is not advisable to handle Database actiity in javascript due to security issues.
Javascript runs on client side machine it should have the least load and computation.
Javascript should be as light as possible. So i suggest you do it in the database itself.

Don't count on JavaScript performance, because it is heavily depend on computer that is running on. I suggest you to store and search on server-side rather than loading heavy payload of data in Browser which is quite restricted to resources of end-user.
Running long loops in JavaScript can lead to an unresponsive and irritating UI. Use Ajax calls to get needed data as a good practice.

Are you using HTML5? Will your users typically have relatively fast multicore computers? If so, a web-worker (http://www.w3schools.com/html/html5_webworkers.asp) might be a way to offload the search to the client while maintaining UI responsiveness.
Note, I've never used a Worker, so this advice may be way off base, but they certainly look interesting for something like this.

In terms of separation of concerns, and recommended best approach, you should be handling that domain-level data retrieval on your server, and relying on the client-side for processing and displaying only the records with which it is concerned.
By populating your client with several thousand records for it to then parse, sort, search, etc., you not only take a huge performance hit and diminish user experience, but you also create many potential security risks. Obviously this also depends on the nature of the data in the application, but for something such as employee records, you probably don't want to be storing that on the client-side. Anyone using the application will then have access to all of that.
The more pragmatic approach to this problem is to have your controller populate the client with only the specific data which pertains to it, eliminating the need for searching through many records. You can also retrieve a single object by making an ajax query to your server to retrieve the data. This has the dual benefit of guaranteeing that you're displaying the current state of the DB, as well as being far more optimized than anything you could ever hope to write in JS.

Manage relations among users in db

I am creating a mock app with user creation/auth/friend in a node js learning exercise. Having spent my time mostly at the front end of things, I am a n00b as far as DBs are concerned. I want to create a user database where I want to keep track of user profiles and their connections/friends.
Primary objective is to load/store users connections in the database.
Fetch this information and give it to the user most efficiently in least number of queries.
I'd really appreciate some help with a DB structure I should be using that can accomplish this. I am using mongodb and node.
Off the top of my head: I can store the user's connections in an object in the "connections" field. But this will involve making a lot of queries to fetch connections' details like their "about me" information - which I can also store in the same object as well.
Confused. Would really appreciate some pointers.

Take a look at the Mongoose ORM. It has a populate method that grabs foreign documents. Lots of other great stuff too.
You could say
Users.find({}).populate('connections').exec(function(err,users) { ... });
Before popualte the users' array of connections was an array of IDs, after, its an array of user documents.

Easiest, Most Efficient way of associating data from different tables Without Associations

This is something that has intrigued me a lot recently. It's a general SQL/Relational Database problem coming from a guy who prefers Mongo.
What I want is, to, as such, associate data from different tables in the most efficient, easiest way, without using associations and assuming I can't restructure or re-model the db.
So, for example, with FQL (which doesn't have associations), if I asked for the name and eid of all the events my current user has been invited to, I'd also like to know whether my current user is going, but that info is in the 'event_member' table.
In this instance I've an interest in another column (rsvp_status) in event_member, one that I'd like to be associated with the columns from event, i.e eid and name.
In this case the instinct may be to say that since every event has a name, an eid and a rsvp_status then we could say sort by eid and then match each nth item (for n=1 to whatever), because there's guaranteed to be the same number, but there are many cases when we can't do that.
And I know I could do separate queries and then iterate through and match them by eid, but basically I'm looking for a generic, simple,efficient solution for the associations idea if one exists. Preferably in javascript.

What you are looking for here is a simple JOIN of two or more tables. http://www.w3schools.com/sql/sql_join.asp
You do not have to have any relations between tables in order to perform JOINS. The relations are just a constraint to ensure that bad/invalid data can't propagete to the tables. For example an event_member with eid of unexisting user. Anyway you are free to JOIN tables as you like :)
Here is a way to connect to Sql Server using javascript How to connect to SQL Server database from JavaScript in the browser?