mysql - 使用 UNION 和 DISTINCT 优化 MySQL 选择查询

Question

我的 PHP 脚本中有一个查询没有返回所需的数据。查询是

select distinct require_category from users_require

返回:

Diet
Experience
MeasurementsGain
MeasurementsLoss
MeasurementsMaintain
WeightGain
WeightLoss
WeightMaintain
Workout

但我只想

Diet
Experience
MeasurementsGain
WeightGain
Workout

我已经改进了我的 mysql 查询并返回了正确的结果，但我认为它的效率不够高:

select distinct require_category from users_require where require_category NOT LIKE '%Weight%' and require_category NOT LIKE '%Measurements%' union select distinct require_category from users_require where require_category = 'WeightGain' or require_category = 'MeasurementsGain'

Answer 1

请尝试以下，

SELECT DISTINCT
require_category FROM users_require WHERE require_category NOT LIKE '%Loss%'
AND require_category NOT LIKE '%Maintain%'