I am having a database having name and hobbies(as multivalued attribute) and I want to find out what is the count of occurence of more than one same value
For example
If this is a sample database
A reading
A dancing
B reading
B dancing
Then the result should be
List of hobbies | Number of occurrence
-----------------|---------------------
reading, dancing | 2
I think you have a query like this:
SELECT hobbies, Count(*) As hNo
FROM t
GROUP BY hobbies
That have a result set like this:
hobbies | hNo
--------+------
reading | 2
dancing | 2
Now for this data-set you can follow answers of this question [Concatenate many rows into a single text string] to have them in one row.
Related
I have a table that looks like the following:
id | cars
1 | John's Honda
2 | Andrew's red lexus
3 | James has a bmw
I need to just get the last word of the "cars" column that shows the actual "car" name
I have tried the followings but I don't get the desired output
select substr(cars, -1)
from t
the code above just shows me the last charater of the column. Later, I tried the following:
select split(cars, ' ')[offset(1)]
from t
however, I got the "Array index 1 is out of bounds (overflow)" error. Can anyone help how this can be achieved with bigquery?
Consider below simple approach
select *,
array_reverse(split(cars, ' '))[offset(0)] as brand
from your_table
if applied to sample data in your question - output is
Note: there are really many ways to accomplish your case - so anoher one would be regexp_extract(cars, r'\b(\w+)$') as brand
I am not sure how to phrase this question so I'll give an example:
Suppose there is a table called tagged that has two columns: tagger and taggee. What would the SQL query look like to return the taggee(s) that are in multiple rows? That is to say, they have been tagged 2 or more times by any tagger.
I would like a 'generic' SQL query and not something that only works on a specific DBMS.
EDIT: Added "tagged 2 or more times by any tagger."
HAVING can operate on the result of aggregate functions. So if you have data like this:
Row tagger | taggee
--------+----------
1. Joe | Cat
2. Fred | Cat
3. Denise | Dog
4. Joe | Horse
5. Denise | Horse
It sounds like you want Cat, Horse.
To get the taggee's that are in multiple rows, you would execute:
SELECT taggee, count(*) FROM tagged GROUP BY taggee HAVING count(*) > 1
That being said, when you say "select only rows with multiple hits for a specific column", which row do you want? Do you want row 1 for Cat, or row 2?
select distinct t1.taggee from tagged t1 inner join tagged t2
on t1.taggee = t2.taggee and t1.tagger != t2.tagger;
Will give you all the taggees who have been tagged by more than one tagger
I am trying to write up a query for wordpress which will give me all the post_id's with the lowest fromprice field for each region. Now the trick is these are custom fields in wordpress, and due to such, the information is stored row based, so there is no region and fromprice columns.
So the data I have is (but of course containing a lot more rows):
Post_ID | Meta_Key | Meta_Value
1 | Region | Location1
1 | FromPrice | 150
2 | Region | Location1
2 | FromPrice | 160
3 | Region | Location2
3 | FromPrice | 145
The query I am endeavoring to build should return the post_id of the "lowest priced" matching post grouped by each region with results like:
Post_ID | Region | From Price
1 | Location1 | 150
3 | Location2 | 145
This will allow me to easily iterate the post_id's and print the required information, in fact, I would be just happy with returning post_id's if the rest is harder, I can then fetch the information independently if need be.
Thanks a lot, tearing my hair out over this one; don't often have to think about shifting results on their side from row based to column based that often, but this time I need it!
So you get an idea of the table structure I have, you can use the below as a guide. I thought I had this, but it turned out yes, this query prints out each distinct region WITH the lowest from price found attached to that post in the region, but the post_id is completely incorrect. I don't know why, it seems to be just getting the first result of the post_id and using that.
SELECT pm.post_id,
pm2.meta_value as region,
MIN(pm.meta_value) as price
FROM `wp_postmeta` pm
inner join `wp_postmeta` pm2
on pm2.post_id = pm.post_id
AND pm2.meta_key = 'region'
AND pm.meta_key = 'fromprice'
group by region
I suggest changing MIN(pm.meta_value) in your query to be MIN(CAST(pm.meta_value AS DECIMAL)). Meta_value is a character field, so your existing query will be returning the minimum string value, not the minimum numeric value; for example, "100" will be deemed to be lower than "21".
EDIT - amended CAST syntax.
It's hard to figure out without being able to execute the query, but would it help to just change your group by to:
group by pm.post_id, region
I want a table structure which can store the details of the student like the below format.
If the student is in
10 th standard -> I need his aggregate % from 1st standard to 9th standard.
5 th standard -> I need his aggregate % from 1st standard to 4th standard.
1 st standard -> No aggregate % has to be displayed.
And the most important thing is ' we need to use only one table'. Please form a table structure with no redundant values.
Any ideas will be greatly appreciated......
No friends this is not a home work. This is asked in Oracle interview, conducted in Hyderabad day before yesterday '24th July, 2010',. He asked me the table structure.
He even did not asked me the query. He asked me how I will design the table. Please advice me.
id | name | grade | aggregate
This would do the trick, id is your primary key, name is students first last name, grade is what grade he is in and aggregate is aggregate % based on the grade.
Fro example some rows might be:
10 | Bill Cosby | 10 | 90
11 | Jerry Seinfeld | 4 | 60
Bill Cosby would have aggregate percent of 90 in grades 1-9, and jerry would have 60 in grades 1-3. In this case it is one table and boils down to you managing the rule of aggregation for this table, since it has to be one table.
If this is an interview question, it looks like they would like to check your knowledge on Nested Tables. Essentially you would have one column as roll number, and other column which is a nested table as Class and Percentage.
I'm very new to SQL and I hope someone can help me with some SQL syntax. I have a database with these tables and fields,
DATA: data_id, person_id, attribute_id, date, value
PERSONS: person_id, parent_id, name
ATTRIBUTES: attribute_id, attribute_type
attribute_type can be "Height" or "Weight"
Question 1
Give a person's "Name", I would like to return a table of "Weight" measurements for each children. Ie: if John has 3 children names Alice, Bob and Carol, then I want a table like this
| date | Alice | Bob | Carol |
I know how to get a long list of children's weights like this:
select d.date,
d.value
from data d,
persons child,
persons parent,
attributes a
where parent.name='John'
and child.parent_id = parent.person_id
and d.attribute_id = a.attribute_id
and a.attribute_type = "Weight';
but I don't know how to create a new table that looks like:
| date | Child 1 name | Child 2 name | ... | Child N name |
Question 2
Also, I would like to select the attributes to be between a certain range.
Question 3
What happens if the dates are not consistent across the children? For example, suppose Alice is 3 years older than Bob, then there's no data for Bob during the first 3 years of Alice's life. How does the database handle this if we request all the data?
1) It might not be so easy. MS SQL Server can PIVOT a table on an axis, but dumping the resultset to an array and sorting there (assuming this is tied to some sort of program) might be the simpler way right now if you're new to SQL.
If you can manage to do it in SQL it still won't be enough info to create a new table, just return the data you'd use to fill it in, so some sort of external manipulation will probably be required. But you can probably just use INSERT INTO [new table] SELECT [...] to fill that new table from your select query, at least.
2) You can join on attributes for each unique attribute:
SELECT [...] FROM data AS d
JOIN persons AS p ON d.person_id = p.person_id
JOIN attributes AS weight ON p.attribute_id = weight.attribute_id
HAVING weight.attribute_type = 'Weight'
JOIN attributes AS height ON p.attribute_id = height.attribute_id
HAVING height.attribute_type = 'Height'
[...]
(The way you're joining in the original query is just shorthand for [INNER] JOIN .. ON, same thing except you'll need the HAVING clause in there)
3) It depends on the type of JOIN you use to match parent/child relationships, and any dates you're filtering on in the WHERE, if I'm reading that right (entirely possible I'm not). I'm not sure quite what you're looking for, or what kind of database you're using, so no good answer. If you're new enough to SQL that you don't know the different kinds of JOINs and what they can do, it's very worthwhile to learn them - they put the R in RDBMS.
when you do a select, you need to specify the exact columns you want. In other words you can't return the Nth child's name. Ie this isn't possible:
1/2/2010 | Child_1_name | Child_2_name | Child_3_name
1/3/2010 | Child_1_name
1/4/2010 | Child_1_name | Child_2_name
Each record needs to have the same amount of columns. So you might be able to make a select that does this:
1/2/2010 | Child_1_name
1/2/2010 | Child_2_name
1/2/2010 | Child_3_name
1/3/2010 | Child_1_name
1/4/2010 | Child_1_name
1/4/2010 | Child_2_name
And then in a report remap it to how you want it displayed