A NoSQL database enables storage and retrieval of data which is displayed in any format other than the tabular storage as used in traditional databases. It has no or lesser dependency on external table to fetch or store data. NoSQL is especially useful in business environments as it handles requirements like: Huge and ever-growing data. . NoSQL Workbench supports Ubuntu 12.04, Fedora 21, and Debian 8 or any newer versions of these Linux distributions. Start the application that you downloaded, and follow the onscreen instructions to install NoSQL Workbench. Hey, depends solely on your requirements i.e. Is your SQL database (1) on a server or (2) held locally via the app? You need to look into connecting up your server to a back end language to talk to your server and give you the data you need. Swift Objective-C API Changes. Framework Security. Secure the data your app manages, and control access to your app. IOS 2.0+ macOS 10.0+ Mac Catalyst 13.0+ tvOS 9.0+ watchOS 2.0+ On This Page. Restrict access to system resources and user data in macOS apps to contain damage if an app becomes compromised.
Developers are doing
|
Column | Type |
---|---|
student id | integer |
course | character varying(40) |
grade | integer |
key | serial |
To work with this table using Swift-Kuery we need to create a class that describes this table. The created class has to be a subclass of the class SwiftKuery.Table. It has to have a field
tableName
which contains the name of the table and one field per column in the table of the type Column.
Here is the class describing the Grades table:
We need to create an instance and we are set:
Let’s start with a simple
Here is how to build this query in Swift-Kuery:
Now let’s add some conditions, e.g., we only want grades above ninety in Chemistry:
Let’s try something a bit more complicated. Suppose we want to retrieve the average grades for courses with an average above ninety, and sort the results by the average ascending. Here is the SQL query we need to build:
Note, that we also round the average grades and alias this column in the result as “average”.
Here is how to create such query using Swift-Kuery:
Here is how to create such query using Swift-Kuery:
As you can see, this is very similar to the SQL query syntax.
Suppose we have another table in our database called Students. This table lists the names of the students along with their student ids:
Column | Type |
---|---|
name | character varying(100) |
student id | integer |
Let’s get the grades in Physics for all the students with the students’ names:
And in Swift-Kuery:
Here is how you insert new values with Swift-Kuery:
We insert a new grade, and get back a new autoincrementing key.
Let’s delete the grades of those students who are not in Students table:
Executing Queries
Until now we have only built queries, now we will also execute them on some database. For that purpose we need to connect to a database using one of Swift-Kuery plugins:
Once connected, we can run our query:
Queries with parameters
Inserting text directly into a query in the code may open us up to SQL Injection attacks. To avoid this problem, queries with parameters should be used. Parameters are values that are inserted when the query is executed and can’t change the clauses of the query.
Let’s go back to the Insert query we created before, and use parameters instead of values:
For PostgreSQL, Swift-Kuery will generate:
And for SQLite the generated query will be:
Please note the difference in the parameter markers for these two databases: PostgreSQL uses
$
to mark parameters in queries, while SQLite uses ?
. Swift-Kuery and its plugins support such syntax differences between the databases. These differences are hidden from you, making it easier to migrate from one database engine to another.
Now let’s see how to pass the actual values:
Next steps
Now that you know how to create and execute SQL queries using Swift-Kuery, you can integrate the backend of your application with relational SQL databases.
For a detailed example on how to work with Swift-Kuery, see the blog Creating a Bookstore application: Interface to SQL and its related github project Bookstore.
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