SQL · Theory

LEFT()()

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LEFT()()

LEFT()() (str) sits in a viva board. Vikram’s job is LEFT str on Vikram's board. Write that first.

Keep LEFT()() (str) small. Vikram should finish LEFT str on Vikram's board in a few lines, not a 40-line dump.

LEFT()() (str) exists so Vikram can keep LEFT str on Vikram's board correct in a viva board.

LEFT()() (str) shows up in a viva board. Name LEFT str on Vikram's board, not “a real-world scenario”.

Don’t do this with LEFT()() (str) — only reciting the name of LEFT str. Interviewers spot it in ten seconds.

After LEFT()() (str), Vikram should still remember only reciting the name of LEFT str.

One breath for LEFT()() (str), then LEFT str on Vikram's board, then only reciting the name of LEFT str. Sit down.

Exam tip

Board: LEFT str on Vikram's board. Dry-run LEFT()() (str). Name the trap: only reciting the name of LEFT str.

LEFT()() — sample query

CREATE TABLE customers (id INTEGER PRIMARY KEY, name TEXT);
CREATE TABLE orders (id INTEGER PRIMARY KEY, customer_id INTEGER, total INTEGER);
INSERT INTO customers VALUES (1, 'Asha'), (2, 'Ravi');
INSERT INTO orders VALUES (10, 1, 500), (11, 1, 200);
SELECT c.name, o.total
FROM customers c
JOIN orders o ON o.customer_id = c.id;

LEFT()() — jOIN combines rows using a match condition between tables.

Short notes

DefLEFT()() (str) — Vikram uses it for LEFT str on Vikram's board in a viva board.
RuleLEFT()() (str) → one LEFT str step Vikram can write from memory.
RememberLEFT()() (str) + InnoDB (a viva board).
UseLEFT()() (str) in a viva board (LEFT str on Vikram's board).
TrapLEFT()() (str) — only reciting the name of LEFT str.
ExLEFT()() (str) → LEFT str on Vikram's board.

CREATE TABLE customers (id INTEGER PRIMARY KEY, name TEXT); CREATE TABLE orders (id INTEGER PRIMARY KEY, customer_id INTEGER, total INTEGER); INSERT INTO customers VALUES (1, 'Asha'), (2, 'Ravi'); INSERT INTO orders VALUES (10, 1, 500), (11, 1, 200); SELECT c.name, o.total FROM customers c JOIN orders o ON o.customer_id = c.id;

LEFT()()

LEFT()() — sample query

Short notes

Questions

LEFT()()

LEFT()() — sample query

Short notes

Questions