having

SQL: HAVING clause

由 半城伤御伤魂 提交于 2019-12-10 10:07:17
问题 See the following SQL statement: SELECT datediff("d", MAX(invoice.date), Now) As Date_Diff , MAX(invoice.date) AS max_invoice_date , customer.number AS customer_number FROM invoice INNER JOIN customer ON invoice.customer_number = customer.number GROUP BY customer.number If the the following was added: HAVING datediff("d", MAX(invoice.date), Now) > 365 would this simply exclude rows with Date_Diff <= 365? What should be the effect of the HAVING clause here? EDIT: I am not experiencing what the

difference between where and having with respect to aliases

由 家住魔仙堡 提交于 2019-12-10 04:35:47
问题 If I create an alias in the select clause then I cannot use it in the where clause because according to the order of execution of sql queries where comes before select . But I can create an alias in the select clause and use it in a having clause though having comes before select . Why is it so? Ex: select type, (case when number>25 then 1 else 0 end) inc from animals where inc='1'; this wont work. But, select type, (case when number>25 then 1 else 0 end) inc from animals having inc='1'; This

mysql基础知识理解和sql题讲解分析面试实战（一）之groupBy&&having

由 旧巷老猫 提交于 2019-12-10 03:19:21
mysql 之groupBy&&having 的使用 groupby和having在什么情况下使用 使用时需要注意什么 groupby和having在什么情况下使用 问题 ：根据平均值分析表 demo :原始表 结果表:根据每位user的rate的平均值更新rate， rate = rate - avg(rate) 实现步骤 step 1 创建表 -若你是想做大数据，一定要控制表字段的大小，字段最好不要为空，为空会导致索引失败 CREATE table userRate( id int(2) NOT null auto_increment, user int(2) not null DEFAULT 0, rate int(2) not null DEFAULT 0, PRIMARY KEY(id) ) step2 插入数据- 注意插入的时候因id是自增长的，所以不用，但是在表后面需填写你要插入的字段名 INSERT into userRate(user,rate) VALUES(1,1),(1,3),(1,2),(2,4),(2,4),(2,5),(2,3); step3 执行sql更新查询 update userRate JOIN (SELECT id,USER,AVG(rate) AS avr from userRate GROUP BY user HAVING user=

mysql group by having min

由 我与影子孤独终老i 提交于 2019-12-09 06:22:14
问题 Below is the table data (a small piece) basically I'm looking to query just the rows with the minimum original_date_ctr when grouped by the accoutn number. I've tried using HAVING(MIN()), and where = Min() and other ways with no luck. The correct result here would give me id_ctr 688, 1204 and 1209 id_ctr account_number_cus original_date_ctr mrc_ctr ------ ------------------ ----------------- ---------- 688 20062 2008-05-17 138.97 1204 151604 2006-08-10 42000.00 1209 151609 2006-06-29 968.68

SELECT From MySQL View With HAVING Clause Returns Empty Result Set

由 安稳与你 提交于 2019-12-09 03:38:03
问题 My business partner and I are having issues selecting from a MySQL view that has a HAVING clause. The query simply selects a few fields from the view, determines a distance dynamically with a few calculations, and aliases it as 'distance' - then limits the results to those rows with a distance less than a supplied variable. The distance is calculated using the Haversine formula, referenced by Google Maps: https://developers.google.com/maps/articles/phpsqlsearch Here is what I know: 1) When

mysql中having和where的区别

由 有些话、适合烂在心里 提交于 2019-12-07 16:03:05
让我们先运行2个sql语句： 1、 SELECT * FROM `welcome` HAVING id >1 LIMIT 0 , 30 2、 SELECT * FROM `welcome` WHERE id >1 LIMIT 0 , 30 查看一下结果吧，怎么样？是不是查询到相同的结果。 让我们再看2个sql语句： 1、 SELECT user, MAX(salary) FROM users GROUP BY user HAVING MAX(salary)>10; 2、 SELECT user, MAX(salary) FROM users GROUP BY user WHERE MAX(salary)>10; 怎么样？看出差别了吗，第一个sql语句可以正常运行【旧版mysql可能会出错】，而第二个则会报错。 看了2个实例之后，我们再来看mysql手册中对having语句的说明： 1、SQL标准要求HAVING必须引用GROUP BY子句中的列或用于总计函数中的列。不过，MySQL支持对此工作性质的扩展，并允许HAVING涉及SELECT清单中的列和外部子查询中的列。 2、HAVING子句必须位于GROUP BY之后ORDER BY之前。 3、如果HAVING子句引用了一个意义不明确的列，则会出现警告。在下面的语句中，col2意义不明确，因为它既作为别名使用，又作为列名使用

Mysql | Faceted search

由 邮差的信 提交于 2019-12-06 22:57:26
I have a fiddle: http://sqlfiddle.com/#!2/46a7b5/18 This request return all attributes. | META_NAME | META_VALUE | COUNT | |----------------|------------|-------| | Car Type | Coupe | 2 | | Car Type | Sedan | 1 | | Color | Black | 1 | | Color | Red | 1 | | Color | White | 1 | | Interior Color | Black | 2 | | Interior Color | Grey | 1 | | Make | BMW | 2 | | Make | Honda | 1 | | Model | 2Series | 1 | | Model | 3Series | 1 | | Model | Civic | 1 | To get searched result I have the request below: SELECT meta_name, meta_value, COUNT(DISTINCT item_id) count FROM meta m JOIN item_meta im ON im.field

MySQL Update Subset Having

由 吃可爱长大的小学妹 提交于 2019-12-06 21:38:13
问题 I have three tables: contacts, domains, and contacts_domains, which form a many-to-many relationship. I would like to run a query that updates the contacts_domains table, but only for domains that have exactly one contact. I know how to SELECT the rows I'm interested in, but not how to UPDATE them. SELECT domain_id, contact_id, dominant FROM contacts_domains GROUP BY domain_id HAVING COUNT(contact_id) = 1 I want to set contacts_domains.dominant = 1 for all these results. Thanks! 回答1: The

How to reduce SQL queries in only one in this case

由 拜拜、爱过 提交于 2019-12-06 15:11:54
问题 I want to save the hassle of doing many querys for the following: I have a table like this: name, age { Mike, 7 Peter, 2 Mario, 1 Tony, 4 Mary, 2 Tom, 7 Jerry, 3 Nick, 2 Albert, 22 Steven, 7 } And I want the following result: Results(custom_text, num) { 1 Year, 1 2 Year, 3 3 Year, 1 4 Year, 1 5 Year, 0 6 Year, 0 7 Year, 3 8 Year, 0 9 Year, 0 10 Year, 0 More than 10 Year, 1 } I know how to do this but in 11 queries :( But how to simplify it? EDIT: Doing the following, I can obtain the non zero

Mysql - find conversation only being held by two users

由 ﹥＞﹥吖頭↗ 提交于 2019-12-06 07:17:30
I have a table called participants with the following fields: id user_id conversation_id The background is that there are conversations with at least two or more participants. I want to find a conversation that has only been held by two specified users, with no other users in the conversation. I have come up with the following: SELECT * FROM participants WHERE user_id = 1 OR user_id = 2 GROUP BY conversation_id HAVING COUNT(*) = 1 Given this content you can see that the users 1 and 2 share a conversation with user 3 (conversation 1), but also have one conversation alone (conversation 2). The
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