This should be an easy thing to do but I seem to keep getting an extra space. Basically what I am trying to do is combine multiple columns into one column. BUT every single one of these columns might be null as well. When I combine them, I also want them to be separated by a space (' ').
What I created is the following query:
select 'All'= ISNULL(Name+' ','')+ISNULL(City+' ','')+ISNULL(CAST(Age as varchar(50))+' ','') from zPerson
and the result is:
All
John Rock Hill 23
Munchen 29
Julie London 35
Fort Mill 27
Bob 29
As you can see: there is an extra space when the name is null. I don't want that.
The initial table is :
id Name City Age InStates AllCombined
1 John Rock Hill 23 1 NULL
2 Munchen 29 0 NULL
3 Julie London 35 0 NULL
4 Fort Mill 27 1 NULL
5 Bob 29 1 NULL
Any ideas?
select 'All'= LTRIM(ISNULL(Name+' ','')+ISNULL(City+' ','')+ISNULL(CAST(Age as varchar(50))+' ','') from zPerson)
SEE LTRIM()
In the data you have posted, the Name column contains no NULLs. Instead, it contains empty strings, so ISNULL(Name+' ','') will evalate to a single space.
The simplest resolution is to change the data so that empty-strings are null. This is appropriate in your case since this is clearly your intention.
UPDATE zPerson SET Name=NULL WHERE Name=''
Repeat this for your City and Age fields if necessary.
Use TRIM() arount the ISNULL() function, or LTRIM() around the entire selected term
Related
Let's say I have the following entries in my database:
Id
Name
12
John Doe
13
Mary anne
13
little joe
14
John doe
In my program I have a string variable that is always capitalized, for example:
myCapString = "JOHN DOE"
Is there a way to retrieve the rows in the table by using a WHERE on the name column with the values capitalized and then matching myCapString?
In this case the query would return two entries, one with id=12, and one with id=14
A solution is NOT to change the actual values in the table.
A general solution in Postgres would be to capitalize the Name column and then do a comparison against an all-caps string literal, e.g.
SELECT *
FROM yourTable
WHERE UPPER(Name) = 'JOHN DOE';
If you need to implement this is Knex, you will need to figure out how to uppercase a column. This might require using a raw query.
Say I have students table with one column named name as follows:
| name |
--------
Jhon
Natalie Kocher
Jonell Dickson
Irvin
Kiara Audet
Shawna Duvall
Cobey Maryellen
Kenny
Lindsy Taylor
How to get all rows that under 6 characters so that I get the following name:
Jhon
Irvin
Kenny
In case that's not possible at least how to sort / set the order of returned rows start from smallest length of chars to the longest.
Thanks,
About SQLite query
Use the length() function:
select t.*
from t
where length(name) < 6;
Or you can use not like:
where name not like '______%' -- there are 6 underscores
Due to the way a particular table is written I need to do something a little strange in SQL and I can't find a 'simple' way to do this
Table
Name Place Amount
Chris Scotland
Chris £1
Amy England
Amy £5
Output
Chris Scotland £1
Amy England £5
What I am trying to do is above, so the null rows are essentially ignored and 'grouped' up based on the Name
I have this working using For XML however it is incredibly slow, is there a smarter way to do this?
This is where MAX would work
select
Name
,Place = Max(Place)
,Amount = Max(Amount)
from
YourTable
group by
Name
Naturally, if you have more than one occurance of a place for a given name, you may get unexpected results.
I am investigating the benefits of Oracle Text search, and currently am looking at collecting search text data from multiple (related) tables and storing the data in the smaller table in a 1-to-many relationship.
Consider these 2 simple tables, house and inhabitants, and there are NEVER any uninhabited houses:
HOUSE
ID Address Search_Text
1 44 Some Road
2 31 Letsby Avenue
3 18 Moon Crescent
INHABITANT
ID House Name Nickname
1 1 Jane Doe Janey
2 1 John Doe JD
3 2 Jo Smythe Smithy
4 2 Percy Plum PC
5 3 Apollo Lander Moony
I want to to write SQL that updates the HOUSE.Search_Text column with text from INHABITANT. Now because this is a 1-to-many, the SQL needs to collate the data in INHABITANT for each matching row in house, and then combine the data (comma separated) and update the Search_Text field.
Once done, the Oracle Text search index on HOUSE.Search_Text will return me HOUSEs that match the search criteria, and I can look up INHABITANTs accordingly.
Of course, this is a very simplified example, I want to pick up data from many columns and Full Text Search across fields in both tables.
With the help of a colleague we've got:
select id, ADDRESS||'; '||Names||'; '||Nicknames as Search_Text
from house left join(
SELECT distinct house_id,
LISTAGG(NAME, ', ') WITHIN GROUP (ORDER BY NAME) OVER (PARTITION BY house_id) as Names,
LISTAGG(NICKNAME, ', ') WITHIN GROUP (ORDER BY NICKNAME) OVER (PARTITION BY house_id) as Nicknames
FROM INHABITANT)
i on house.id = i.house_id;
which returns:
1 44 Some Road; Jane Doe, John Doe; JD, Janey
2 31 Letsby Avenue; Jo Smythe, Percy Plum; PC, Smithy
3 18 Moon Crescent; Apollo Lander; Moony
Some questions:
Is this an efficient query to return this data? I'm slightly
concerned about the distinct.
Is this the right way to use Oracle Text search across multiple text fields?
How to update House.Search_Text with the results above? I think I need a correlated subquery, but can't quite work it out.
Would it be more efficient to create a new table containing House_ID and Search_Text only, rather than update House?
I am trying to find the ANSI way to write the T-SQL 'IS NULL'. (corrected, was 'IN NULL')
Some posts on the internet say you can use coalesce to make it work like 'IS NULL'
The reason I like to do this: portable code. And the query must return the rows that are NULL.
So far I created this:
SELECT empid,
firstname,
lastname,
country,
coalesce(region,'unknown') AS regions ,
city
FROM HR.Employees
The result set looks like:
empid firstname lastname country regions city
1 Sara Davis USA WA Seattle
2 Don Funk USA WA Tacoma
3 Judy Lew USA WA Kirkland
4 Yael Peled USA WA Redmond
5 Sven Buck UK unknown London
6 Paul Suurs UK unknown London
7 Russell King UK unknown London
8 Maria Cameron USA WA Seattle
9 Zoya Dolgopyatova UK unknown London
I identified the rows that are NULL, but how do I filter them out of this set?
Both IS NULL and COALESCE are ANSI standard and available in almost all reasonable databases. The construct that you want, I think, is:
where region IS NULL
This is standard syntax.
To have COALESCE work like IS NULL requires a value that you know is not in the data:
where coalesce(region, '<null>') <> '<null>'
However, you would need different values for dates and numbers.
You seem to be confusing IS NULL (a predicate that checks to see if a value is null) and the T-SQL specific function ISNULL(value, replace) (no space and parameters after it), which is similar, but not identical to COALESCE.
Please see SQL - Difference between COALESCE and ISNULL? for details on how COALESCE and ISNULL differ for T-SQL.
Minor differences like what type is returned and what happens when all the arguments are null aside, ISNULL is a function that returns the first argument if it is not null, or the second argument if it is. COALESCE returns the first non-null argument (it can take more than two).
As a result, each of these might be used to solve your problem in different ways and with slightly different results.
IS NULL is valid ANSI SQL-92, is called the null predicate.
<null predicate> ::= <row value constructor> IS [ NOT ] NULL
See SQL-92, paragraph 8.6.
So WHEREcolumn nameIS NULL is perfectly valid.
The bit where ANSI SQL treats NULL values different from T-SQL is when you write WHERE column name = NULL or WHERE column name <> NULL. See SET ANSI NULLS (Transact-SQL).