Key Concepts and Terms

Understanding the Datasets Module

The Datasets Module enables users to interact with SQL databases seamlessly, allowing them to retrieve and manipulate data within their applications for:

• Generate Custom Visualizations,
• Implement Custom Logic,
• Set Up Dynamic Data Processing, Alarming, or Storage operations.

The module supports real-time Tags within query strings, and manages files and recipes in ASCII, Unicode, or XML formats.

Data Utilization

The data retrieved from databases can be utilized in various ways throughout your project, for example:

• In the Displays Module: Visualization tools like DataGrids can present query results on screens and dashboards, creating custom views of the data that are accessible and easy to understand for your users.
• In the Scripting Module: Custom scripts can reference query results and trigger specific actions, such as sending notifications, updating tags, or performing calculations, thereby implementing complex logic based on database data.
• In the Alarm Module: Data can be used to configure or update alarm conditions, triggers, and actions, enabling the creation of dynamic alarm systems that respond to data changes.

Various modules can also add data to your SQL databases. For instance, the Displays Module can log operation inputs and commands, the Scripting Module can calculate analytics, and the Alarm and Historian Modules can retain long-term records and audit trails. 

Processing Data Requests

Datasets Data Server Service

The Datasets Data Server Service ensures high performance and seamless integration while exchanging structured collections of data in real-time. It efficiently processes data requests from other modules, enabling connectivity with various components such as HMI/SCADA screens, scripting, and reporting tools.

Default Databases Used When Running the Solution

The Dataset module also serves as a data storage configuration hub for other modules. The Alarm and Historian modules, which generate events and records for long-term retention, utilize the Dataset module for defining data storage. Similarly, the Security Module can utilize user definitions from an external database defined within the Dataset module.

Data Source Virtualization

Data Source Virtualization is an advanced feature that simplifies data management across multiple data sources. It provides a unified interface for accessing, querying, and manipulating data, regardless of the underlying data storage technology.

This feature allows modifications to the underlying data sources repositories without impacting the rest of the application. Keywords: Agnostic, Flexible, Easy Maintenance, Centralized Management.

→ Read more about Dataset Advanced Topics.

Configuring the Datasets Module

Configuration Workflow

The typical configuration workflow for the Dataset module has the following sequence:

Managing DB Connections

There are four database connections pre-defined in any new solution.

When using SQLite databases, the Dataset Module can automatically create the database locally if it doesn't already exist. For other database types, the database itself must already exist before you set your connection.

→ Read more about Dataset DBs.

DatasetQueries Configuration

Use the DatasetQueries to define SQL Statements, for queries and stored procedures to execute in connection of the created DatasetDB databases. 

→ Read more about DatasetsQueries

DatasetTables Configuration

Use the DatasetTables to access or exchange data with databases tables, with simplified query syntax. It allows allow insert new rows directly on database tables.

→ Read more about DatasetTables.

DatasetFiles Configuration

The DatasetFiles are used to customize file interactions in the Dataset Module. With this feature you can read or write realtime tags to ASCII, Unicode and XAML files.

→ Read more about DatasetFiles.

Working with the Datasets module

Runtime Execution

When executing the solution, there is an in fracture of services allowing to manage the access to the database, and to transport that information to where it was requested.

For instance, to show a DatasetQuery result in a HTML5 page, that request first goes to the Server, which request to the Database (that can be in another computer), and the information flows back to requests. 

As this operations can time, it is very important to understand some aspects of the Dataset Module execution, including the concept of  synchronous vs asynchronous calls.

The page Datasets Module Execution 

Monitoring the Datasets Module

Intra-Module Interaction

The Datasets module easily integrates with other modules within the software environment. Here are some examples of how to use the Dataset module in conjunction with other modules:

• Displays Module: Visualization tools like Data Grids can present query results on screens and dashboards, creating custom views of the data that are accessible and easy to understand for your users.
• Scripting Module: Custom scripts can reference query results and trigger specific actions, such as sending notifications, updating tags, or performing calculations, thereby implementing complex logic based on database data.
• Alarm Module: Data can be used to configure or update alarm conditions, triggers, and actions, enabling the creation of dynamic alarm systems that respond to data changes
• Unified Namespaces Module: You can utilize Tags from your project as dynamic placeholders within SQL queries or file names. This capability facilitates real-time data manipulation within the query strings. Moreover, you can map the results of the queries to Tags or employ Tags to populate values when inserting or modifying existing records. 

The Datasets module drives bi-directional real-time communication between all Project Modules and the SQL databases. By leveraging these integration options, users can gain greater insight and control over their data sources within the platform. They can execute SQL queries and trigger actions based on query results, providing robust tools for working with data.

External System Interaction

The Dataset module enables seamless interaction with external databases, enhancing data integration and accessibility. The following is a list of possible databases you can connect:

• SQL Server
• PostgreSQL
• Excel

Datasets Advanced Topics

Datasets Module Execution

The Dataset module facilitates efficient database interactions by utilizing TServer services, manageing synchronous and asynchronous executions for optimal performance.

→ Read more about Databases Connection And Interactions.

Data Management

The Dataset Module offers versatile methods for managing data and concurrency within solutions, including Data Table tags and Async Contents.

→ Read more about Data Management.

Datasets Runtime Attributes

The Datasets Namespace exposes properties and methods from the .NET objects used by the Historian Module execution. You can use these properties and methods on your Displays or to create Scripts and Alarms.

→ Read more about Dataset Runtime Attributes.

Preventing SQL Injections

→ See page Datasets Advanced Topics

Network Gateway Access And Time Zone Handling

→ See page Datasets Advanced Topics

Backup Of Solutions SQLite Data Bases

→See page Datasets Advanced Topics

Best Practices and Troubleshooting

Common Issues and Solutions

Connection loss between project and database

Database Timeout Configuration: The database may have a timeout setting that automatically disconnects idle connections after a certain period of time. It's recommended to check the database's timeout setting and adjust it, if necessary, to ensure that the connection remains active overnight.

Power Settings: It's also suggested to check the computer's power settings to ensure that it's not entering sleep or hibernation mode during a certain idle moment, which could cause loss of connection to the database. Adjusting these settings to keep the computer active during these idle moments may resolve the issue.

Database Connection Problem

In the DB configuration, there is always a "Test" button to ensure that the connection is happening correctly. When there is a problem, the return of this button is an error message, usually returned by the database provider itself. The most common errors are: invalid user, invalid password, computer without access to the database, incorrect form of authentication.

Issue: Error accessing the Database Table

Once the connection is established, the Table configuration is specific to a table. In the "Table" combobox, the list of available tables automatically appears. It is possible, via script, to change which table will be accessed. However, care must be taken that the table exists and that the configuration is done using the correct name. The same care must be taken when Queries are used, as it is the user's responsibility to type the correct table name, as well as the syntax of the separators.

Error in the Syntax of the Query

It is the user's responsibility to type the correct SQLStatement of a query using the QueryBuilder. Table name, column, values, all can generate an error if used incorrectly. For example: comparing different types may not return the expected result, strings in general should be in single quotes. The separators and clauses available can vary between databases, for example:

SQLServer

SELECT TOP 10 * FROM table WHERE column = value

SQLite

SELECT * FROM table WHERE column = value LIMIT 10;

Oracle

SELECT * FROM table WHERE column = value AND ROWNUM <= 10;

or new Oracle version

SELECT * FROM table WHERE column = value FETCH FIRST 10 ROWS ONLY;

IBM DB2

SELECT * FROM table WHERE column = value FETCH FIRST 10 ROWS ONLY;

ServerIP without TWebServer Running on the Remote Machine

In some cases, the computer may not have access to the database. In this case, it is possible to create a gateway, routing the commands to be executed on the computer that has access to the database. The ServerIP field should be configured with the IP and port (<IP>:<port>), pointing to this computer that has access permission. This computer must have the software with the TWebServer running installed. It will automatically perform this gateway service and send the commands to the database.

DataTable Returned NULL

When a query is returned null, some error has occurred. Some common errors include: connection failure with the database, table not found, Dataset module is not running, incorrect query syntax. Check the return of the method using WithStatus when using a synchronous method or use the LastStatus and LastStatusMessage property when using asynchronous mode.

DataTable Returned with 0 Rows

When this happens, in general, there is a connection with the database and the table name is correct. In this case, the search condition is usually wrong, or the table is really empty. Check if the column names are correct and if the separators and clauses are valid.

Dataset Module is Down

Although the TServer is responsible for forwarding requests to the database, the management and communication with the TServer is done by the Dataset module, as well as the treatment of responses. Therefore, if you are having basic problems with access and execution of database access, the first thing to check is whether the module is set up to run and is actually running.

Very High Response Time

Sometimes, it may seem that access to the database is not being made, but what might actually be happening is that some accesses can return a very large amount of data, or the database may be overloaded, or with a bad configuration, causing it to have a low performance. Or even, the network itself can be overloaded and slow, and all these factors can impact the response time. In these cases, it is important to execute the Query directly in the database environment to be sure that the problem is not on the side of the database. Do this and check how long the database itself takes to execute the query. It is also worth checking the volume of data exchanged to have an idea of ??the related side effects.

** What are all these hashtags below for? **

#Update of a table with the wrong schema (select before update)

The Dataset module uses ADO technology, and many things are resolved at the level of this API. When we are going to perform an Update on a table, the schema of the table and controls in the .Net DataTable type are used. Therefore, if you are going to perform an update passing a Tag or .net DataTable object as a parameter, it is important that this object respects the schema of the destination Table in the database. Normally, a Select command must have been given at some point to obtain the correct schema used by the bank. After this, it is easy to add, remove, and modify values in this DataTable and update it back to the physical table in the database.

#Where condition CaseSensitive

Case sensitivity in a WHERE clause depends on the database and the configuration of the database you are using. For example, in MySQL, queries are case-insensitive by default, which means 'abc' and 'ABC' would be considered equal. However, this can be changed with specific database settings. In SQL Server, case sensitivity is also determined by the database configuration. In PostgreSQL, queries are case-sensitive by default, so 'abc' and 'ABC' would be considered different. Therefore, it really depends on the specific database and the settings of that database. If you need to ensure case-insensitivity in a query, you can use functions like UPPER() or LOWER() to convert all values to upper or lower case before comparison. For example:

SELECT * FROM table WHERE LOWER(column) = LOWER(value);

This query will return records where the column matches the value, regardless of capitalization.

#Performance

The Dataset module's performance depends on many factors, including database performance, network latency, and the complexity of executing SQL queries. The platform will minimize overhead and execute queries as efficiently as possible. However, ultimately, the performance of the Dataset module is tied to these external factors. It's essential to design your database schema and queries with performance in mind and consider investing in high-quality hardware and network infrastructure to ensure optimal performance.

Best Practices and Recommendations

#Error Handling

Error handling in the Dataset module is straightforward. Suppose an error occurs during the execution of a command. The error message will update the module's Error property (Last Status). You can monitor this property to handle errors in your application. Furthermore, suppose an error occurs during the execution of a synchronous method. In that case, the process will return an empty Data Table, and update the Error property. Alternatively, you can call methods like SelectCommandWithStatus, where the status will be an output parameter in the method.

These are some of the key points you should keep in mind while using the Dataset module. It's a powerful tool that provides much flexibility. However, it also requires careful use and understanding of its features and limitations. Always keep best practices in mind when designing and implementing your database interactions. Feel free to seek expert advice if you need clarification on anything.

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