I have data like abc1, abc2, abcK. The result after sort should display like abcK, abc1, abc2.
Is there any way to achieve this?
Specify a different collating sequence, either by using ALTER SESSION to change the collating sequence for your entire session or by using NLSSORT to change the collating sequence for a single ORDER BY. For example,
SELECT *
FROM YOUR_TABLE
ORDER BY NLSSORT(YOUR_COLUMN, 'NLS_SORT=WEST_EUROPEAN')
will order letters before numbers. SQLFiddle here
Share and enjoy.
You could use a CASE expression in the ORDER BY clause.
For example,
order by
case when translate(column,'x0123456789','x') is null then 2
else 1
end, column;
The TRANSLATE would evaluate the pure strings as NULL. Thus, the case would return 2, else for all others, 1. Thus, any string having a number, i.e. alphanumeric values would be below the pure alphabets.
Related
The field name is message, table name is log.
Data Examples:
Values for message:
"(wsname,cmdcode,stacode,data,order_id) values (hyd-l904149,2,1,,1584425657892);"
"(wsname,cmdcode,stacode,data,order_id) values (hyd-l93mt54,2,1,,1584427657892);"
(command_execute,order_id,workstation,cmdcode,stacode,application_to_kill,application_parameters) values (kill, 1583124192811, hyd-psag314, 10, 2, tsws.exe, -u production ); "
and in log table i need to get separated column wsname with values as hyd-l904149 and hyd-l93mt54 and hyd-psag314, column cmdcode with values as 2,2 and 10 and column stacode with values as 1,1 and 2, e.g.:
wsname cmdcode stacode
hyd-l904149 2 1
hyd-l93mt54 2 1
hyd-psag314 10 2
Use regexp_matches to extract left and right part of values clause, then regexp_split_to_array to split these parts by commas, then filter rows containing wsname using = any(your_array) construct, then select required columns from array.
Or - alternative solution - fix data to be syntactically valid part of insert statement, create auxiliary tables, insert data into them and then just select.
As in comment section I mentioned about inbuilt function in posgressql
split_part(string,delimiter, field_number)
http://www.sqlfiddle.com/#!15/eb1df/1
As the json capabilities of the un-supported version 9.3 are very limited, I would install the hstore extension, and then do it like this:
select coalesce(vals -> 'wsname', vals -> 'workstation') as wsname,
vals -> 'cmdcode' as cmdcode,
vals -> 'stacode' as stacode
from (
select hstore(regexp_split_to_array(e[1], '\s*,\s*'), regexp_split_to_array(e[2], '\s*,\s*')) as vals
from log l,
regexp_matches(l.message, '\(([^\)]+)\)\s+values\s+\(([^\)]+)\)') as x(e)
) t
regexp_matches() splits the message into two arrays: one for the list of column names and one for the matching values. These arrays are used to create a key/value pair so that I can access the value for each column by the column name.
If you know that the positions of the columns are always the same, you can remove the use of the hstore type. But that would require quite a huge CASE expression to test where the actual columns appear.
Online example
With a modern, supported version of Postgres, I would use jsonb_object(text[], text[]) passing the two arrays resulting from the regexp_matches() call.
I store the following rows in my table ('DataScreen') under a JSONB column ('Results')
{"Id":11,"Product":"Google Chrome","Handle":3091,"Description":"Google Chrome"}
{"Id":111,"Product":"Microsoft Sql","Handle":3092,"Description":"Microsoft Sql"}
{"Id":22,"Product":"Microsoft OneNote","Handle":3093,"Description":"Microsoft OneNote"}
{"Id":222,"Product":"Microsoft OneDrive","Handle":3094,"Description":"Microsoft OneDrive"}
Here, In this JSON objects "Id" amd "Handle" are integer properties and other being string properties.
When I query my table like below
Select Results->>'Id' From DataScreen
order by Results->>'Id' ASC
I get the improper results because PostgreSql treats everything as a text column and hence does the ordering according to the text, and not as integer.
Hence it gives the result as
11,111,22,222
instead of
11,22,111,222.
I don't want to use explicit casting to retrieve like below
Select Results->>'Id' From DataScreen order by CAST(Results->>'Id' AS INT) ASC
because I will not be sure of the datatype of the column due to the fact that JSON structure will be dynamic and the keys and values may change next time. and Hence could happen the same with another JSON that has Integer and string keys.
I want something so that Integers in Json structure of JSONB column are treated as integers only and not as texts (string).
How do I write my query so that Id And Handle are retrieved as Integer Values and not as strings , without explicit casting?
I think your assumtions about the id field don't make sense. You said,
(a) Either id contains integers only or
(b) it contains strings and integers.
I'd say,
If (a) then numerical ordering is correct.
If (b) then lexical ordering is correct.
But if (a) for some time and then (b) then the correct order changes, too. And that doesn't make sense. Imagine:
For the current database you expect the order 11,22,111,222. Then you add a row
{"Id":"aa","Product":"Microsoft OneDrive","Handle":3095,"Description":"Microsoft OneDrive"}
and suddenly the correct order of the other rows changes to 11,111,22,222,aa. That sudden change is what bothers me.
So I would either expect a lexical ordering ab intio, or restrict my id field to integers and use explicit casting.
Every other option I can think of is just not practical. You could, for example, create a custom < and > implementation for your id field which results in 11,111,22,222,aa. ("Order all integers by numerical value and all strings by lexical order and put all integers before the strings").
But that is a lot of work (it involves a custom data type, a custom cast function and a custom operator function) and yields some counterintuitive results, e.g. 11,111,22,222,0a,1a,2a,aa (note the position of 0a and so on. They come after 222).
Hope, that helps ;)
If Id always integer you can cast it in select part and just use ORDER BY 1:
select (Results->>'Id')::int From DataScreen order by 1 ASC
If the email column is NULL, I want to have the phone number value in the PRIMARY_Contact column. I am using CASE expression, but could not do it properly.
You may be looking for COALESCE. It will return the first non-null value from a selection. It's actually just shorthand for CASE, but may be easier for you to implement.
In your example, perhaps that would look like this:
SELECT COALESCE(EMAIL,PRIMARY_CONTACT)
Check out https://msdn.microsoft.com/en-us/library/ms190349.aspx for more details.
I am working on a database that (hopefully) will end up using a primary key with both numbers and letters in the values to track lots of agricultural product. Due to the way in which the weighing of product takes place at more than one facility, I have no other option but to maintain the same base number but use letters in addition to this base number to denote split portions of each lot of product. The problem is, after I create record number 99, the number 100 suddenly floats up and underneath 10. This makes it difficult to maintain consistency and forces me to replace this alphanumeric lot ID with a strictly numeric value in order to keep it sorted (which I use "autonumber" as the data type). Either way, I need the alphanumeric lot ID, and so having 2 ID's for the same lot can be confusing for anyone inputting values into the form. Is there a way around this that I am just not seeing?
If you're using query as a data source then you may try to sort it by string converted to number, something like
SELECT id, field1, field2, ..
ORDER BY CLng(YourAlphaNumericField)
Edit: you may also try Val function instead of CLng - it should not fail on non-numeric input
Why not properly format your key before saving ? e.g: "0000099". You will avoid a costly conversion later.
Alternatively, you could use 2 fields as the composite PK. One with the Number (as Long) and one with the Location (as String).
How would you search for the longest match within a varchar variable? For example, table GOB has entries as follows:
magic_word | prize
===================
sh| $0.20
sha| $0.40
shaz| $0.60
shaza| $1.50
I would like to write a plpgsql function that takes amongst other arguments a string as input (e.g. shazam), and returns the 'prize' column on the row of GOB with the longest matching substring. In the example shown, that would be $1.50 on the row with magic_word shaza.
All the function format I can handle, it's just the matching bit. I can't think of an elegant solution. I'm guessing it's probably really easy, but I am scratching my head. I don't know the input string at the start, as it will be derived from the result of a query on another table.
Any ideas?
Simple solution
SELECT magic_word
FROM gob
WHERE 'shazam' LIKE (magic_word || '%')
ORDER BY magic_word DESC
LIMIT 1;
This works because the longest match sorts last - so I sort DESC and pick the first match.
I am assuming from your example that you want to match left-anchored, from the beginning of the string. If you want to match anywhere in the string (which is more expensive and even harder to back up with an index), use:
...
WHERE 'shazam' LIKE ('%' || magic_word || '%')
...
SQL Fiddle.
Performance
The query is not sargable. It might help quite a bit if you had additional information, like a minimum length that you could base an index on, to reduce the number of rows to consider. It needs to be criteria that gets you less than ~ 5% of the table to be effective. So, initials (a natural minimum pick) may or may not be useful. But two or three letters at the start might help quite a bit.
In fact you could optimize this iteratively. Something along the line of:
Try a partial index of words with 15 letters+
If not found, try 12 letters+
If not found, try 9 letters+
...
A simple case of what I outlined in this related answer on dba.SE:
Can spatial index help a “range - order by - limit” query
Another approach would be to use a trigram index. You'd need the additional module pg_trgm for that. Normally you would search with a short pattern in a table with longer strings. But trigrams work for your reverse approach, too, with some limitations. Obviously you couldn't match a string with just two characters in the middle of a longer string using trigrams ... Test for corner cases.
There are a number of answers here on SO with more information. Example:
Effectively query on column that includes a substring
Advanced solution
Consider the solution under this closely related question for a whole table of search strings. Implemented with a recursive CTE:
Longest Prefix Match
How about
1
select max(FOO.matchingValue)
from
(
select magic_word as matchingValue
from T
where substr( "abracadabra", 1, length(magic_word)) = magic_word
)
as FOO
2
select prize from
T
join
(
select max(FOO.matchingValue) as MaxValue
from
(
select magic_word as matchingValue
from T
where substr( "abracadabra", 1, length(magic_word)) = magic_word
)
as FOO
) as BAR
on BAR.MaxValue = T.magic_word