SQL · Theory

Show Columns

Theory

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Show Columns

Sara only reaches for Show Columns when Show Columns on Sara's board has to stay correct in a first job task.

Show Columns order: meaning → one Show Columns step Sara can write from memory → one limit. Dumping ten features helps nobody.

Without Show Columns, a first job task gets messy and Show Columns on Sara's board is hard to trust.

Use Show Columns when Show Columns on Sara's board must stay clear. If a simpler SQL step works, use that instead.

Show Columns miss — only reciting the name of Show Columns. Fix it before you talk about advanced SQL.

Show Columns is not a lonely heading. Sara ties it to Show Columns on Sara's board.

One breath for Show Columns, then Show Columns on Sara's board, then only reciting the name of Show Columns. Sit down.

Exam tip

Say Show Columns in one breath, then one Show Columns step Sara can write from memory, then only reciting the name of Show Columns.

Show Columns — sample query

-- Show Columns
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Show Columns: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefShow Columns — Sara uses it for Show Columns on Sara's board in a first job task.
RuleShow Columns → one Show Columns step Sara can write from memory.
RememberShow Columns + an index (a first job task).
UseShow Columns in a first job task (Show Columns on Sara's board).
TrapShow Columns — only reciting the name of Show Columns.
ExShow Columns → Show Columns on Sara's board.

-- Show Columns CREATE TABLE demo ( id INTEGER PRIMARY KEY, label TEXT NOT NULL, qty INTEGER DEFAULT 0 ); INSERT INTO demo (id, label, qty) VALUES (1, 'alpha', 2), (2, 'beta', 5); SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Show Columns

Show Columns — sample query

Short notes

Questions

Show Columns

Show Columns — sample query

Short notes

Questions