SELECT IFNULL(NULL,’Value is NULL’) AS result1,

IFNULL(1 > 2, ‘NULL result’) AS result2;

mysql> SELECT NULLIF(TRUE,TRUE) AS istrue,

NULLIF(TRUE,FALSE) AS isfalse,

NULLIF(TRUE,NULL) AS isnull;

MySQL has four logic control operators: AND, OR, NOT, and XOR. Three of these operators also have

shorthand notations: && (AND), || (OR), ! (NOT). These shorthand notations should not be confused

with the Bit operators, which are single characters of & and |.

SELECT IF (2 > 1,’2 is greater than 1’,’2 is not greater than 1’) AS answer;

mysql> SET @value=CONVERT(RAND()* 10, UNSIGNED INTEGER);

mysql> SELECT @value,

-> CASE

-> WHEN @value < 3 THEN ‘Value is < 3’

-> WHEN @value > 6 THEN ‘Value is > 6’

-> WHEN @value = 3 OR @value = 6 THEN ‘Value is 3 or 6’

-> ELSE ‘Value is 4 or 5’

-> END;

mysql> SELECT IFNULL(NULL,’Value is NULL’) AS result1,

IFNULL(1 > 2, ‘NULL result’) AS result2;

mysql> CREATE TABLE example (

-> currency ENUM(‘USD’,’CAD’,’AUD’) NOT NULL

-> ) ENGINE=InnoDB DEFAULT CHARSET latin1;

mysql> ALTER TABLE flags

-> ADD FOREIGN KEY (color)

-> REFERENCES colors (color)

-> ON DELETE CASCADE;

mysql> SHOW WARNINGS;

mysql> SET SESSION sql_mode=’TRADITIONAL’;

sql_mode=NO_ENGINE_SUBSTITUTION

SELECT DISTINCT f.color

FROM flags f

WHERE EXISTS

(SELECT 1

FROM colors c

WHERE c.color = f.color);

SELECT DISTINCT f.country,

(SELECT GROUP_CONCAT(color)

FROM flags f2

WHERE f2.country = f.country) AS colors

FROM flags f;