3. Your First SELECT
Idea: SELECT asks for columns from a table. A basic query states the columns and table name.
Shape of a Basic Query
SELECT Column1, Column2 FROM TableName;
This returns all rows for those columns (until we add filters later).
Plain Explanation
You are saying: "Server, give me these columns from that table." No more, no less.
Placeholders for Examples
Coming soon: running a SELECT against a sample Products table.
Advanced Deep Dive ADVANCED
Column Order vs Storage: The order you list columns dictates output column order, not physical storage. Physical order is abstracted by row format and indexes.
SELECT * Tradeoffs: Handy for exploration but can cause wider I/O, break app code after schema changes, and block covering index usage. Prefer explicit columns.
Logical Processing: The FROM phase (including JOINs) logically occurs before the SELECT list is evaluated, so aliases in the SELECT list cannot be used in WHERE in the same query.
Projection & Performance: Reducing column list can cut memory usage and network transfer, especially with big text or binary columns.
TOP with ORDER BY: To get deterministic subsets you almost always pair TOP with an explicit ORDER BY; otherwise row selection can vary between executions.