I have a column in a table that contains numeric data separated by a hyphen. I need to split this data into three columns so each part of this numeric value is in a separate column. The specific data is for learning purposes but I've also seen databases where name fields are one column instead of three (e.g. "FirstMiddleLast" instead of "First", "Middle", Last").
Here is a sample of the numeric value:
1234-56-78
I would like to split that so I have three columns
1234 | 56 | 78
How can I achieve this?
Try this (Sql Fiddle here);
declare #s varchar(50)='1234-56-78'
select left(#s,charindex('-',#s,1)-1) Col1,
substring(#s,charindex('-',#s,1)+1, len(#s)-charindex('-',reverse(#s),1)-
charindex('-',#s,1)) Col2,
right(#s,charindex('-',reverse(#s),1)-1) Col3
--results
Col1 Col2 Col3
1234 56 78
Related
When I created the table Tab, I specified the columns as string,
Tab: ([Key1:string()] Col1:string();Col2:string();Col3:string())
But the column datatype (t) is empty. I suppose specifying the column as string has no effect.
meta Tab
c t f a
--------------------
Key1
Col1
Col2
Col3
After I do a bulk upsert in Java...
c.Dict dict = new c.Dict((Object[]) columns.toArray(new String[columns.size()]), data);
c.Flip flip = new c.Flip(dict);
conn.c.ks("upsert", table, flip);
The datatypes are all symbols:
meta Tab
c t f a
--------------------
Key1 s
Col1 s
Col2 s
Col3 s
How can I specify the datatype of the columns as string and have it remain as string?
You cant define a column of the empty table with as strings as they are merely lists of lists of characters
You can just set them as empty lists which is what your code is doing.
But the column will then take on the type of whatever data is inserted into it.
Real question is what is your java process sending symbols when it should be sending strings. You need to make the change there before publishing to KDB
Note if you define as chars you still wont be able to upsert strings
q)Tab: ([Key1:`char$()] Col1:`char$();Col2:`char$();Col3:`char$())
q)Tab upsert ([Key1:enlist"test"] Col1:enlist"test";Col2:enlist"test";Col3:enlist "test")
'rank
[0] Tab upsert ([Key1:enlist"test"] Col1:enlist"test";Col2:enlist"test";Col3:enlist "test")
^
q)Tab: ([Key1:()] Col1:();Col2:();Col3:())
q)Tab upsert ([Key1:enlist"test"] Col1:enlist"test";Col2:enlist"test";Col3:enlist "test")
Key1 | Col1 Col2 Col3
------| --------------------
"test"| "test" "test" "test"
KDB does not allow to define column types as list during creation of table. So that means you can not define your column type as String because that is also a list.
To do that only way is to define column as empty list like:
q) t:([]id:`int$();val:())
Then when you insert data to this table the column will automatically take type of that data.
q)`t insert (4;"row1")
q) meta t
c | t f a
---| -----
id | i
val| C
In your case, one option is to send string data from your Java process as mentioned by user 'emc211' or other option is to convert your data to string in KDB process before insertion.
I have column like
Column1 column 2
Audy. 123
Baza.z. 675
Sco,da#. 432
Here I am trying
Select column2 from table where lower(column1)='audy';
select column2 from table where lower(column1) regexp'[.,]' ='audy';
I need column data with out special characters in it using either sql or postgre sql and should take regexp from where condition only.
You can use regex_replace:
select column2
from table
where regexp_replace(lower(column1), '\W', '', 'g') = 'audy'
The regex \W matches any character that is not a letter or number. The flag 'g' (global) means remove all matches, not just the first one.
I have a table with many(+1000) columns and rows(~1M). The columns have either the value 1 , or are NULL.
I want to be able to select, for a specific row (user) retrieve the column names that have a value of 1.
Since there are many columns on the table, specifying the columns would yield a extremely long query.
You're doing something SQL is quite bad at - dynamic access to columns, or treating a row as a set. It'd be nice if this were easier, but it doesn't work well with SQL's typed nature and the concept of a relation. Working with your data set in its current form is going to be frustrating; consider storing an array, json, or hstore of values instead.
Actually, for this particular data model, you could probably use a bitfield. See bit(n) and bit varying(n).
It's still possible to make a working query with your current model PostgreSQL extensions though.
Given sample:
CREATE TABLE blah (id serial primary key, a integer, b integer, c integer);
INSERT INTO blah(a,b,c) VALUES (NULL, NULL, 1), (1, NULL, 1), (NULL, NULL, NULL), (1, 1, 1);
I would unpivot each row into a key/value set using hstore (or in newer PostgreSQL versions, the json functions). SQL its self provides no way to dynamically access columns, so we have to use an extension. So:
SELECT id, hs FROM blah, LATERAL hstore(blah) hs;
then extract the hstores to sets:
SELECT id, k, v FROM blah, LATERAL each(hstore(blah)) kv(k,v);
... at which point your can filter for values matching the criteria. Note that all columns have been converted to text, so you may want to cast it back:
SELECT id, k FROM blah, LATERAL each(hstore(blah)) kv(k,v) WHERE v::integer = 1;
You also need to exclude id from matching, so:
regress=> SELECT id, k FROM blah, LATERAL each(hstore(blah)) kv(k,v) WHERE v::integer = 1 AND
k <> 'id';
id | k
----+---
1 | c
2 | a
2 | c
4 | a
4 | b
4 | c
(6 rows)
In a table I have comma separated values and I have to change these values into rows.
Ex: MSGVALUES column
145,24,56,78
23,45,67
Expected output for this
MSGVALUES column
145
24
56
78
23
45
67
I got the above result by using table valued function(CSV) from Google search.
select * from table (CSV('10,20,'34',',')
If I execute CSV function then I am getting the result like
1
20
34
Now my actual requirement is I have to apply the above CSV function to my column name ie.MSG VALUE column. Assume my table name is CODEDESC
so you'd join the table() cast to your table like:
select csv.*
from your_tab t, table(csv(t.msgvalues, ',')) csv;
I'm trying to find a way to use Perl to further process a PostgreSQL output. If there's a better way to do this via PostgreSQL, please let me know. I basically need to choose certain columns (Realtime, Value) in a file to concatenate certains columns to create a row while keeping ID and CAT.
First time posting, so please let me know if I missed anything.
Input:
ID CAT Realtime Value
A 1 time1 55
A 1 time2 57
B 1 time3 75
C 2 time4 60
C 3 time5 66
C 3 time6 67
Output:
ID CAT Time Values
A 1 time 1,time2 55,57
B 1 time3 75
C 2 time4 60
C 3 time5,time6 66,67
You could do this most simply in Postgres like so (using array columns)
CREATE TEMP TABLE output AS SELECT
id, cat, ARRAY_AGG(realtime) as time, ARRAY_AGG(value) as values
FROM input GROUP BY id, cat;
Then select whatever you want out of the output table.
SELECT id
, cat
, string_agg(realtime, ',') AS realtimes
, string_agg(value, ',') AS values
FROM input
GROUP BY 1, 2
ORDER BY 1, 2;
string_agg() requires PostgreSQL 9.0 or later and concatenates all values to a delimiter-separated string - while array_agg() (v8.4+) creates am array out of the input values.
About 1, 2 - I quote the manual on the SELECT command:
GROUP BY clause
expression can be an input column name, or the name or ordinal number
of an output column (SELECT list item), or ...
ORDER BY clause
Each expression can be the name or ordinal number of an output column
(SELECT list item), or
Emphasis mine. So that's just notational convenience. Especially handy with complex expressions in the SELECT list.