SQL · Theory

SPACE()()

Theory

167/439

SPACE()()

SPACE() returns n spaces. You use it in SELECT (and sometimes WHERE/UPDATE). It does not change stored data unless you UPDATE … SET col = SPACE(col).

Board: SELECT CONCAT(name, SPACE(2), city); 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). Not a table of ‘space’.

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

On the example next to this theory: SPACE()(): create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Exam tip

Say what SPACE returns, then SELECT CONCAT(name, SPACE(2), city);

SPACE()() — sample query

-- SPACE()()
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;

SPACE()(): create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefSPACE() returns n spaces.
RuleSELECT CONCAT(name, SPACE(2), city);
TrapNot a table of ‘space’.

SQL · Theory

SPACE()()

← All stacks

Theory

167/439

SPACE()()

SPACE() returns n spaces. You use it in SELECT (and sometimes WHERE/UPDATE). It does not change stored data unless you UPDATE … SET col = SPACE(col).

Board: SELECT CONCAT(name, SPACE(2), city); 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). Not a table of ‘space’.

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

On the example next to this theory: SPACE()(): create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Exam tip

Say what SPACE returns, then SELECT CONCAT(name, SPACE(2), city);

SPACE()() — sample query

-- SPACE()()
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;

SPACE()(): create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefSPACE() returns n spaces.
RuleSELECT CONCAT(name, SPACE(2), city);
TrapNot a table of ‘space’.

SPACE()()

SPACE()() — sample query

Short notes

Questions

SPACE()()

SPACE()() — sample query

Short notes

Questions