having-clause

问题 I have the below table Table 1 Id WFID data1 data2 1 12 'd' 'e' 1 13 '3' '4f' 1 15 'e' 'dd' 2 12 'f' 'ee' 3 17 'd' 'f' 2 17 'd' 'f' 4 12 'd' 'f' 5 20 'd' 'f' From this table I just want to select the rows which has 12 and 17 only exclusively. Like from the table I just want to retrieve the distinct id's 2,3 and 4. 1 is excluded because it has 12 but also has 13 and 15. 5 is excluded because it has 20. 2 in included because it has just 12 and 17. 3 is included because it has just 17 4 is

问题 I am trying the WHERE clause to filter out other data I dont want. SELECT `post_id`, MAX(CASE WHEN `meta_key` = 'vlaue_1' THEN `meta_value` ELSE NULL END) as 'Customer', MAX(CASE WHEN `meta_key` = 'value_2' THEN `meta_value` ELSE NULL END) as 'DeliveryDate', MAX(CASE WHEN `meta_key` = 'value_3' THEN `meta_value` ELSE NULL END) as 'DeliveryTime', MAX(CASE WHEN `meta_key` = 'vlaue_4' THEN `meta_value` ELSE NULL END) as 'DeliveryType' FROM wp_postmeta WHERE 'Customer' > 0 GROUP BY `post_id`

问题 this is my fiddle https://dbfiddle.uk/?rdbms=mysql_5.7&fiddle=7c549a3de0c8002ec43381462ba6a801 let's assume I have the data like this CREATE TABLE test ( ID INT, user_id INT, createdAt DATE, status_id INT ); INSERT INTO test VALUES (1, 12, '2020-01-01', 4), (2, 12, '2020-01-03', 7), (3, 12, '2020-01-06', 7), (4, 13, '2020-01-02', 5), (5, 13, '2020-01-03', 6), (6, 14, '2020-03-03', 8), (7, 13, '2020-03-04', 4), (8, 15, '2020-04-04', 7), (9, 14, '2020-03-02', 6), (10, 14, '2020-03-10', 5), (11,

来源： https://stackoverflow.com/questions/63460464/having-vs-where-vs-group-by-clauses-when-to-use-them-and-if-you-use

来源： https://stackoverflow.com/questions/63460464/having-vs-where-vs-group-by-clauses-when-to-use-them-and-if-you-use

来源： https://stackoverflow.com/questions/63547666/select-occurences-of-a-combination-of-columns-with-a-minimum-condition-on-the-co

问题 I need to use an alias in the WHERE clause, but It keeps telling me that its an unknown column. Is there any way to get around this issue? I need to select records that have a rating higher than x. Rating is calculated as the following alias: sum(reviews.rev_rating)/count(reviews.rev_id) as avg_rating 回答1: You could use a HAVING clause, which can see the aliases, e.g. HAVING avg_rating>5 but in a where clause you'll need to repeat your expression, e.g. WHERE (sum(reviews.rev_rating)/count

问题 I need to use an alias in the WHERE clause, but It keeps telling me that its an unknown column. Is there any way to get around this issue? I need to select records that have a rating higher than x. Rating is calculated as the following alias: sum(reviews.rev_rating)/count(reviews.rev_id) as avg_rating 回答1: You could use a HAVING clause, which can see the aliases, e.g. HAVING avg_rating>5 but in a where clause you'll need to repeat your expression, e.g. WHERE (sum(reviews.rev_rating)/count

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: SQL: What's the difference between HAVING and WHERE? I have seen various discussions on WHERE and HAVING . I still have a question: is HAVING used only when considering aggregates, or can it be used in more general terms: whenever you have created or aliased a field in your query? I know that WHERE should always be used when possible. 回答1: HAVING specifies a search for something used in the SELECT statement. In

问题 i need to find in sakila data base the longest rental period of a movie. i have trie this: SELECT DISTINCT customer.first_name FROM rental, customer WHERE rental.customer_id = customer.customer_id GROUP BY rental.rental_id HAVING ( rental.return_date - rental.rental_date ) =( SELECT MAX(countRental) FROM ( SELECT ( rental.return_date - rental.rental_date ) AS countRental FROM rental, customer GROUP BY rental.rental_id ) AS t1 ) but i am getting the error: 1054 - Unknown column 'rental.return