Tool to define screen relationships diagrams? [closed]

1. Is SqlDBM free?
2. What type of diagram helps capture things to be stored and the relationship between things?

Is SqlDBM free?

SqlDBM free trial is interactive and can work well in a pinch. But if you want to use it for any length of time, you'll have to pay for one of their plans, the least expensive of which is $25 per month.

What type of diagram helps capture things to be stored and the relationship between things?

What is an ER diagram? An Entity Relationship (ER) Diagram is a type of flowchart that illustrates how “entities” such as people, objects or concepts relate to each other within a system.