join

问题 I have a bunch of candidates, who have had one or more jobs, each with a company, using some skills. Bad ascii art follows: --------------- --------------- | candidate 1 | | candidate 2 | --------------- \ -------------- / \ | ------- -------- etc |job 1| | job 2 | ------- --------- / \ / \ --------- --------- --------- -------- |company | | skills | |company | | skills | --------- --------- ---------- ---------- Here's my database: mysql> describe jobs; +--------------+---------+------+-----

问题 I am not able to understand how Cartesian product works. Consider the simple schema: mysql> select * from account; +----------------+-------------+---------+ | account_number | branch_name | balance | +----------------+-------------+---------+ | A101 | Downtown | 500 | | A102 | Perryridge | 400 | | A201 | Brighton | 900 | | A215 | Mianus | 700 | | A217 | Brighton | 750 | | A222 | Redwood | 700 | | A305 | Round Hill | 350 | +----------------+-------------+---------+ 7 rows in set (0.00 sec)

问题 I'm working on a training tracker program and I'm at a point where I can't figure out the SQL query. I have 3 tables: employees, trainingRecords, masterList . employees and trainingRecords are related through the empID fkey. trainingRecords and masterList are related through the TID fkey. Right now the training records table is blank because nothing has been entered (all employees have no training). I want to populate a listbox with all of the items in the masterList that are unaccounted for

问题 I'm working on a training tracker program and I'm at a point where I can't figure out the SQL query. I have 3 tables: employees, trainingRecords, masterList . employees and trainingRecords are related through the empID fkey. trainingRecords and masterList are related through the TID fkey. Right now the training records table is blank because nothing has been entered (all employees have no training). I want to populate a listbox with all of the items in the masterList that are unaccounted for

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 1 year ago . Improve this question I have the following example of a string: "label1, label2, label3, label4, label5" Now, because this will be used as an object initialising a jquery plugin, it needs to look like this: 'label1','label2','label3','label4','label5' I already managed to split the

问题 Greetings Overflowers, I need to query against objects with many/complex spacial conditions. In relational databases that is translated to many joins (possibly 10+). I'm new to this business and wondering whether to go with MS SQL Server 2008 R2 or Oracle 11g or document-based solutions such as RavenDB or simply go with some spacial database (GIS)... Any thoughts ? Regards UPDATE: Thank you all for your answers. Would anybody opt for document/spatial databases ? My database would consist of

问题 I've gotten some good help on here with some tricky stuff like this, so thought I'd have you guys take a look and see if this is even possible. I have two tables in MySQL .. company and resources ... companies can have multiple resources .. so ... company -------- companyId (primary/auto inc) companyName resources --------- resourceId (primary/auto inc) companyId resourceName I'd like to query the two tables and group it so the results look like this ... Example... Company Name ResourceName1

问题 I've gotten some good help on here with some tricky stuff like this, so thought I'd have you guys take a look and see if this is even possible. I have two tables in MySQL .. company and resources ... companies can have multiple resources .. so ... company -------- companyId (primary/auto inc) companyName resources --------- resourceId (primary/auto inc) companyId resourceName I'd like to query the two tables and group it so the results look like this ... Example... Company Name ResourceName1

问题 Here are examples of the 3 tables I'm working with. Teams +----+------+ | id | name | +----+------+ | 1 | abc | | 2 | def | | 3 | ghi | +----+------+ Members +----+-----------+----------+---------+ | id | firstname | lastname | team_id | +----+-----------+----------+---------+ | 1 | joe | smith | 1 | | 2 | jared | robinson | 1 | | 3 | sarah | cole | 3 | | 4 | jaci | meyers | 2 | +----+-----------+----------+---------+ Goals +----+-----------+ | id | member_id | +----+-----------+ | 1 | 3 | |

问题 My problem is the following: Lets say I have an existing dataframe with the following columns: UID, foo, result. Result is already partially filled. A second model now predicts additional rows, generating a second dataframe containing a UID and a result column: (Code to reproduce at bottom) ## df_main ## UID foo result ## <dbl> <chr> <chr> ## 1 1 moo Cow ## 2 2 rum <NA> ## 3 3 oink <NA> ## 4 4 woof Dog ## 5 5 hiss <NA> ## new_prediction ## UID result ## <dbl> <chr> ## 1 3 Pig ## 2 5 Snake I