SQL · Theory

like()()

Theory

147/439

like()()

LIKE() is a MySQL string function — it takes text and returns text or a number. You use it in SELECT (and sometimes WHERE/UPDATE). It does not change stored data unless you UPDATE … SET col = LIKE(col).

Board: SELECT LIKE(name) FROM students; Run it. Say the result out loud. If the column is NULL, the result is often NULL — wrap with IFNULL if you need a blank instead.

String indexes in MySQL start at 1, not 0 (SUBSTR, INSTR, LEFT). NULL input often yields NULL. Try it on one row first.

Interview — name LIKE, one argument list, one example on the students table. Don’t recite every string function.

On the example next to this theory — like()() — wHERE combines predicates with AND/OR; LIKE does pattern match.

Exam tip

Say what LIKE returns, then SELECT LIKE(name) FROM students;

like()() — sample query

CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, price REAL);
INSERT INTO products VALUES (1, 'Pen', 10), (2, 'Book', 200), (3, 'Bag', 50);
SELECT * FROM products
WHERE price BETWEEN 20 AND 150 AND name LIKE 'B%';

like()() — wHERE combines predicates with AND/OR; LIKE does pattern match.

Short notes

DefLIKE() is a MySQL string function — it takes text and returns text or a number.
RuleSELECT LIKE(name) FROM students;
TrapNULL input often yields NULL. Try it on one row first.

SQL · Theory

like()()

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Theory

147/439

like()()

Board: SELECT LIKE(name) FROM students; Run it. Say the result out loud. If the column is NULL, the result is often NULL — wrap with IFNULL if you need a blank instead.

String indexes in MySQL start at 1, not 0 (SUBSTR, INSTR, LEFT). NULL input often yields NULL. Try it on one row first.

Interview — name LIKE, one argument list, one example on the students table. Don’t recite every string function.

On the example next to this theory — like()() — wHERE combines predicates with AND/OR; LIKE does pattern match.

Exam tip

Say what LIKE returns, then SELECT LIKE(name) FROM students;

like()() — sample query

CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT, price REAL);
INSERT INTO products VALUES (1, 'Pen', 10), (2, 'Book', 200), (3, 'Bag', 50);
SELECT * FROM products
WHERE price BETWEEN 20 AND 150 AND name LIKE 'B%';

like()() — wHERE combines predicates with AND/OR; LIKE does pattern match.

Short notes

DefLIKE() is a MySQL string function — it takes text and returns text or a number.
RuleSELECT LIKE(name) FROM students;
TrapNULL input often yields NULL. Try it on one row first.

like()()

like()() — sample query

Short notes

Questions

like()()

like()() — sample query

Short notes

Questions