I have a column "pnum" in a "test" table.
I'd like to replace the leading "9" in pnum with "*" for every record.
testdb=# select * from test limit 5;
id name pnum
===========================================
1 jk 912312345
2 tt 9912333333
I would like the pnums to look like this:
id name pnum
===========================================
1 jk *12312345
2 tt *912333333
How would I do something like this in postgres?
EDIT 1:
I have tried something like this so far:
select id, name, '*' && substring(pnum FROM 2 FOR CHAR_LENGTH(pnum)-1 ) from test limit 3;
Also tried this:
select id, name, '*' || substring(pnum FROM 2 FOR CHAR_LENGTH(pnum)-1 ) from test limit 3;
Neither one has worked...
EDIT 2:
I figured it out:
select id, name, '*'::text || substring(pnum FROM 2 FOR CHAR_LENGTH(pnum)-1 ) from test limit 3;
See function regexp_replace(string text, pattern text, replacement text [, flags text]) String Functions and Operators
SELECT regexp_replace('9912333333', '^[9]', '*');
regexp_replace
----------------
*912333333
You can use Postgres' string manipulation functions for this. In your case "Substring" and "Char_Length"
'*' || Substring(<yourfield> FROM 2 FOR CHAR_LENGTH(<yourfield>)-1) as outputfield
Related
I have 2 varchar(64) values that are decimals in this case (say COLUMN1 and COLUMN2, both varchars, both decimal numbers(money)). I need to create a where clause where I say this:
COLUMN1 < COLUMN2
I believe I have to convert these 2 varchar columns to a different data types to compare them like that, but I'm not sure how to go about that. I tried a straight forward CAST:
CAST(COLUMN1 AS DECIMAL(9,2)) < CAST(COLUMN2 AS DECIMAL(9,2))
But I had to know that would be too easy. Any help is appreciated. Thanks!
You can create a UDF like this to check which values can't be cast to DECIMAL
CREATE OR REPLACE FUNCTION IS_DECIMAL(i VARCHAR(64)) RETURNS INTEGER
CONTAINS SQL
--ALLOW PARALLEL -- can use this on Db2 11.5 or above
NO EXTERNAL ACTION
DETERMINISTIC
BEGIN
DECLARE NOT_VALID CONDITION FOR SQLSTATE '22018';
DECLARE EXIT HANDLER FOR NOT_VALID RETURN 0;
RETURN CASE WHEN CAST(i AS DECIMAL(31,8)) IS NOT NULL THEN 1 END;
END
For example
CREATE TABLE S ( C VARCHAR(32) );
INSERT INTO S VALUES ( ' 123.45 '),('-00.12'),('£546'),('12,456.88');
SELECT C FROM S WHERE IS_DECIMAL(c) = 0;
would return
C
---------
£546
12,456.88
It really is that easy...this works fine...
select cast('10.15' as decimal(9,2)) - 1
from sysibm.sysdummy1;
You've got something besides a valid numerical character in your data..
And it's something besides leading or trailing whitespace...
Try the following...
select *
from table
where translate(column1, ' ','0123456789.')
<> ' '
or translate(column2, ' ','0123456789.')
<> ' '
That will show you the rows with alpha characters...
If the above does't return anything, then you've probably got a string with double decimal points or something...
You could use a regex to find those.
There is a built-in ability to do this without UDFs.
The xmlcast function below does "safe" casting between (var)char and decfloat (you may use as double or as decimal(X, Y) instead, if you want). It returns NULL if it's impossible to cast.
You may use such an expression twice in the WHERE clause.
SELECT
S
, xmlcast(xmlquery('if ($v castable as xs:decimal) then xs:decimal($v) else ()' passing S as "v") as decfloat) D
FROM (VALUES ( ' 123.45 '),('-00.12'),('£546'),('12,456.88')) T (S);
|S |D |
|---------|------------------------------------------|
| 123.45 |123.45 |
|-00.12 |-0.12 |
|£546 | |
|12,456.88| |
PostgreSql gives me this error when i try to cast a TEXT colum to a integer.
select pro_id::integer from mmp_promocjas_tmp limit 1;
This colum contains only digits, valid integer. How can "1" be invalid integer?
select pro_id, length(pro_id) ,length(trim(pro_id)) from mmp_promocjas_tmp limit 1;
outputs:
1 | 2 | 2
Query select pro_id from mmp_promocjas_tmp where trim(pro_id) = '1' shows nothing.
I tried to remove whitespaces, without no result:
select pro_id from mmp_promocjas_tmp where regexp_replace(trim(pro_id), '\s*', '', 'g')
There are probably spurious invisible contents in the column.
To make them visible, try a query like this:
select pro_id, c,lpad(to_hex(ascii(c)),4,'0') from (
select pro_id,regexp_split_to_table(pro_id,'') as c
from (select pro_id from mmp_promocjas_tmp limit 10) as s
) as g;
This will show the ID and each character its contains, both as a character and as its hexadecimal code in the repertoire.
I have a column in my table having values of format:
COURSE_214/MODULE_5825/SUBMODULE_123/..../GOAL_124/ACTIVITY_125.
I need value for goal i.e 124 from goal_124. I am planning to use 'regexp_split_to_array' but don't know how to use elements from array.
I am using postgres 9.2.
You can use split_part like so:
select split_part(split_part('COURSE_214/MODULE_5825/SUBMODULE_123/..../GOAL_124/ACTIVITY_125', '/GOAL_', 2), '/', 1)
i.e.
select split_part(split_part(fieldname, '/GOAL_', 2), '/', 1)
Result:
124
Using json_object():
select json_object(string_to_array(translate(params, '_', '/'), '/'))
from test
json_object
------------------------------------------------------------------------------------------------
{"COURSE" : "214", "MODULE" : "5825", "SUBMODULE" : "123", "GOAL" : "124", "ACTIVITY" : "125"}
(1 row)
select json_object(string_to_array(translate(params, '_', '/'), '/'))->>'GOAL' as goal
from test
goal
------
124
(1 row)
The column has a format suitable for json. I would suggest to change the type of the column to jsonb. The first query may be used as a converter.
After the conversion you would access the parameters in an easy way, e.g.:
select *
from test
where params->>'COURSE' = '214'
and (params->>'GOAL')::int > 120;
Simple select of all GOAL_ parameters (if there are more than one)
select ltrim(elem, 'GOAL_')
from (
select unnest(string_to_array(params, '/')) elem
from test
) sub
where elem like 'GOAL_%'
You may try using regular expressions, getting the string between slashes
select substring(your_column from '^.*/(.*)/.*$') from your_table
If you expect to find in that part the GOAL value, use
select substring(your_column from '/GOAL_(.*)/') from your_table
So I have a in my Postgresql:
TAG_TABLE
==========================
id tag_name
--------------------------
1 aaa
2 bbb
3 ccc
To simplify my problem,
What I want to do is SELECT 'id' from TAG_TABLE when a string "aaaaaaaa" contains the 'tag_name'.
So ideally, it should only return "1", which is the ID for tag name 'aaa'
This is what I am doing so far:
SELECT id FROM TAG_TABLE WHERE 'aaaaaaaaaaa' LIKE '%tag_name%'
But obviously, this does not work, since the postgres thinks that '%tag_name%' means a pattern containing the substring 'tag_name' instead of the actual data value under that column.
How do I pass the tag_name to the pattern??
You should use tag_name outside of quotes; then it's interpreted as a field of the record. Concatenate using '||' with the literal percent signs:
SELECT id FROM TAG_TABLE WHERE 'aaaaaaaa' LIKE '%' || tag_name || '%';
And remember that LIKE is case-sensitive. If you need a case-insensitive comparison, you could do this:
SELECT id FROM TAG_TABLE WHERE 'aaaaaaaa' LIKE '%' || LOWER(tag_name) || '%';
A proper way to search for a substring is to use position function instead of like expression, which requires escaping %, _ and an escape character (\ by default):
SELECT id FROM TAG_TABLE WHERE position(tag_name in 'aaaaaaaaaaa')>0;
I personally prefer the simpler syntax of the ~ operator.
SELECT id FROM TAG_TABLE WHERE 'aaaaaaaa' ~ tag_name;
Worth reading through Difference between LIKE and ~ in Postgres to understand the difference.
`
In addition to the solution with 'aaaaaaaa' LIKE '%' || tag_name || '%' there
are position (reversed order of args) and strpos.
SELECT id FROM TAG_TABLE WHERE strpos('aaaaaaaa', tag_name) > 0
Besides what is more efficient (LIKE looks less efficient, but an index might change things), there is a very minor issue with LIKE: tag_name of course should not contain % and especially _ (single char wildcard), to give no false positives.
SELECT id FROM TAG_TABLE WHERE 'aaaaaaaa' LIKE '%' || "tag_name" || '%';
tag_name should be in quotation otherwise it will give error as tag_name doest not exist
I have the following heap of text:
"BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,
URLConnectionSample,ShortVersion,1.0,Version,1.0,BundleSize,155648,DynamicSize,
16384,Identifier,com.IdentifierForVendor3,Name,IdentifierForVendor3,ShortVersion,
1.0,Version,1.0,".
What I'd like to do is extract data from this in the following manner:
BundleSize:155648
DynamicSize:204800
Identifier:com.URLConnectionSample
Name:URLConnectionSample
ShortVersion:1.0
Version:1.0
BundleSize:155648
DynamicSize:16384
Identifier:com.IdentifierForVendor3
Name:IdentifierForVendor3
ShortVersion:1.0
Version:1.0
All tips and suggestions are welcome.
It isn't quite clear what do you need to do with this data. If you really need to process it entirely in the database (looks like the task for your favorite scripting language instead), one option is to use hstore.
Converting records one by one is easy:
Assuming
%s =
BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,URLConnectionSample,ShortVersion,1.0,Version,1.0
SELECT * FROM each(hstore(string_to_array(%s, ',')));
Output:
key | value
--------------+-------------------------
Name | URLConnectionSample
Version | 1.0
BundleSize | 155648
Identifier | com.URLConnectionSample
DynamicSize | 204800
ShortVersion | 1.0
If you have table with columns exactly matching field names (note the quotes, populate_record is case-sensitive to key names):
CREATE TABLE data (
"BundleSize" integer, "DynamicSize" integer, "Identifier" text,
"Name" text, "ShortVersion" text, "Version" text);
You can insert hstore records into it like this:
INSERT INTO data SELECT * FROM
populate_record(NULL::data, hstore(string_to_array(%s, ',')));
Things get more complicated if you have comma-separated values for more than one record.
%s = BundleSize,155648,DynamicSize,204800,Identifier,com.URLConnectionSample,Name,URLConnectionSample,ShortVersion,1.0,Version,1.0,BundleSize,155648,DynamicSize,16384,Identifier,com.IdentifierForVendor3,Name,IdentifierForVendor3,ShortVersion,1.0,Version,1.0,
You need to break up an array into chunks of number_of_fields * 2 = 12 elements first.
SELECT hstore(row) FROM (
SELECT array_agg(str) AS row FROM (
SELECT str, row_number() OVER () AS i FROM
unnest(string_to_array(%s, ',')) AS str
) AS str_sub
GROUP BY (i - 1) / 12) AS row_sub
WHERE array_length(row, 1) = 12;
Output:
"Name"=>"URLConnectionSample", "Version"=>"1.0", "BundleSize"=>"155648", "Identifier"=>"com.URLConnectionSample", "DynamicSize"=>"204800", "ShortVersion"=>"1.0"
"Name"=>"IdentifierForVendor3", "Version"=>"1.0", "BundleSize"=>"155648", "Identifier"=>"com.IdentifierForVendor3", "DynamicSize"=>"16384", "ShortVersion"=>"1.0"
And inserting this into the aforementioned table:
INSERT INTO data SELECT (populate_record(NULL::data, hstore(row))).* FROM ...
the rest of the query is the same.