Database ideas & Delphi wiring

Grade 12 IT connects Delphi to a database (usually a Microsoft Access .mdb/.accdb file at school). The vocabulary:

• Table — data arranged in rows and columns (like tblLearners).
• Record — one row: everything about one learner.
• Field — one column: Surname, ITMark…
• Primary key — the field that uniquely identifies each record (LearnerID). No duplicates, never empty.

The Delphi components that do the talking, as wired in the exam skeletons:

• TADOConnection — connects the program to the database file.
• TADOQuery — holds and runs your SQL.
• TDataSource + TDBGrid — pipe the results onto the form as a grid.

And the two ways to fire SQL — this distinction is asked constantly:

// SELECT returns rows -> Open
qryLearners.SQL.Text := 'SELECT * FROM tblLearners';
qryLearners.Open;

// INSERT / UPDATE / DELETE change data -> ExecSQL
qryLearners.SQL.Text := 'DELETE FROM tblLearners WHERE ITMark < 50';
qryLearners.ExecSQL;

One Access habit worth knowing: Boolean (Yes/No) fields can be tested as WHERE Paid = True — and because True is stored as a number, WHERE Paid = 1 works too. Both forms work here as well.