问题
SELECT
SQL_CALC_FOUND_ROWS a.* ,
zn.`name` AS zone_name,
c.`name` AS carrier_name,
CASE type
WHEN type=1 THEN 'General day'
ELSE 'Special date' END AS type_changed,
CASE week_day
WHEN week_day = -1 THEN 'notset'
WHEN week_day = 1 THEN 'monday'
WHEN week_day = 2 THEN 'tuesday'
WHEN week_day = 3 THEN 'wednesday'
WHEN week_day = 4 THEN 'thursday'
WHEN week_day = 5 THEN 'friday'
WHEN week_day = 6 THEN 'saturday'
WHEN week_day = 7 THEN 'sunday' END AS week_day_mod ,
IF(date = '0001-01-01 00:00:0', '--', DATE(date)) AS date_mod, IF(is_working_day = 1 ,'working day', 'day off') AS is_working_day_mod
FROM `ps_deliverytime_table` a
LEFT JOIN ps_zone AS zn ON(a.`id_zone` = zn.`id_zone`)
LEFT JOIN ps_carrier AS c ON(a.`id_carrier` = c.`id_carrier`)
WHERE 1 ORDER BY a.`id_time_table` ASC LIMIT 0,50
When week day is equal 1 it works fine but in other case it do not working
回答1:
When you put column name after CASE, you shouldn't use WHEN column = value, just use WHEN value, because it automatically compares the column to each value in the WHEN clauses.
CASE type
WHEN 1 THEN 'General day'
ELSE 'Special date'
END AS type_changed,
CASE week_day
WHEN -1 THEN 'notset'
WHEN 1 THEN 'monday'
WHEN 2 THEN 'tuesday'
WHEN 3 THEN 'wednesday'
WHEN 4 THEN 'thursday'
WHEN 5 THEN 'friday'
WHEN 6 THEN 'saturday'
WHEN 7 THEN 'sunday'
END AS week_day_mod ,
When you do both, you're testing week_day = (week_day = -1), week_day = (week_day = 1), etc. It works on Monday because 1 = (1 = 1) is equivalent to 1 = 1, which is true; but on Tuesday, it's 2 = (2 = 2), which is equivalent to 2 = 1, which is false.
来源：https://stackoverflow.com/questions/31681541/mysql-case-not-working