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Hands-On Mobile and Embedded Development with Qt 5

You're reading from   Hands-On Mobile and Embedded Development with Qt 5 Build apps for Android, iOS, and Raspberry Pi with C++ and Qt

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Product type Paperback
Published in Apr 2019
Publisher Packt
ISBN-13 9781789614817
Length 368 pages
Edition 1st Edition
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Author (1):
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Lorn Potter Lorn Potter
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Lorn Potter
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Table of Contents (21) Chapters Close

Preface 1. Section 1: Making Great UIs FREE CHAPTER
2. Standard Qt Widgets 3. Fluid UI with Qt Quick 4. Graphical and Special Effects 5. Input and Touch 6. Section 2: Networking, Connectivity, Sensors, and Automation
7. Qt Network for Communication 8. Connectivity with Qt Bluetooth LE 9. Machines Talking 10. Where Am I? Location and Positioning 11. Section 3: Other APIs Qt SQL, Qt Multimedia, and Qt Purchasing
12. Sounds and Visions - Qt Multimedia 13. Remote Databases with Qt SQL 14. Enabling In-App Purchases with Qt Purchasing 15. Section 4: Mobile Deployment and Device Creation
16. Cross Compiling and Remote Debugging 17. Deploying to Mobile and Embedded 18. Universal Platform for Mobiles and Embedded Devices 19. Building a Linux System 20. Other Books You May Enjoy

Executing queries

So far, we have been running queries, but not getting any data in return. One of the points of a database is to query for data, not just to enter it. What fun would it be if we could only input data? The Qt API has a way to accommodate the different syntax and millions of ways a query can be made. Most of the time, it is specific to the type of data you need to be returned, but also specific to the database data itself. Luckily, QSqlQuery is general enough that the query parameter is a string.

QSqlQuery

To retrieve data, execute a query using QsqlQuery and then operate on the records using the following functions:

  • first()
  • last()
  • next()
  • previous()
  • seek(int)

The first() and last() functions will...

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