SkillCoded

SQL Fundamentals

Relational Data, Tables, Rows, and Keys

Build a clear relational model by separating tables, rows, columns, keys, relationships, constraints, stored data, and query results.

Beginner13 min read
SQL Fundamentals lessonRelational data foundationsPractice

UNTIMED COACHING

Practice before the pressure

Use feedback to correct the model, not merely memorize an option position.

GUIDED PRACTICE

Practice the lesson questions

Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.

CONCEPT MODELS

See the lesson as a system

Use these visual guides to connect the key ideas before answering the questions.

Read a relational tableSeparate the table's subject, one stored row, the column rule, and the result produced from valid data.
Read a relational tableA table structure contains row data governed by a column decision and produces a verified result.
Table structureTable organizes related row records
Row dataData represents one stored subject
Column decisionDecision defines acceptable field values
Verified resultResult preserves the declared structure
Connect parent and child rowsA parent table owns the primary key, and a child value reaches it through a checked table connection.
Connect parent and child rowsA parent table exposes a primary key, a table connection carries the child reference, and an integrity check validates it.
Parent tableTable owns the referenced row
Primary keyValue identifies one parent row
Table connectionConnection links matching key values
Integrity checkCheck rejects unmatched references