A use case analysis allows you to understand the functional user requirements on the modeled system. During the analysis, you will identify the actors and specify their interactions with the system using use cases. Use cases are detailed using a flow of events.
If you want to design a data model for your database, you should use an entity-relationship diagram (also known by ERD acronym). It may be used for conceptual, logical, and also physical data models. Alternatively, you may also use a UML class diagram for the same purpose.
Regular expressions can be transformed into a state machine diagram. It is possible to map regex syntax to states and transitions.
There are multiple options how you can join rows of two entities into a single result set. It depends on whether you want to have all data from left entity, right entity, both entities or you want to get common data.
UML is used for designing of various software aspects. It provides a notation for structure and behavior modeling. There are 7 structure diagrams and 7 behavior diagrams.
Software development is a complicated process because it produces complicated things that should look very simple. A lot of disasters and mistakes may occur during it. Check this list to avoid common complications in your software projects.
Some modules and concepts are needed in almost every software. This article lists the most common ones.