I am creating a search tool for Postgres. It will have several text entries (one for each table column). When the text entry is blank, I want the query to match each and every table entry. Is this possible? I have tried:
SELECT name FROM contacts WHERE surname = '*';
SELECT name FROM contacts WHERE surname = *;
As you can imagine, this returns nothing since there is no surname of *, and the second query is invalid. Any ideas?
EDIT:
Because of the nature of what I am doing, a SELECT name FROM contacts is not sufficient. I guess I could make it work, but it would be ugly. I want a WHERE for every column in the table, but if the search for any given column is an empty string, I want it to fetch every entry in the table.
OK, so I found my answer here. The correct code is:
SELECT name FROM contacts WHERE surname ~* '';
returns all entries
SELECT name FROM contacts WHERE surname ~* 'John Doe';
returns entries that have a surname of John Doe.
I want the query to match each and every table entry
Just use SELECT without WHERE surname clause. Simple as that.
SELECT name FROM contacts
But if you want to use one query, you can do it this way:
cur.execute(
"""SELECT name FROM contacts
WHERE (CASE WHEN %(entry)s != '' THEN surname = %(entry)s ELSE true END)"""
, {'entry': "John Doe"}
)
As for your answer, you used regular expressions matching. In the question you never mentioned it. So I assume it's not what you wanted. Regular expressions have specific syntax, and if some invalid regex format is entered into the text entry, the query will fail.
Related
I have a problem, I need to count the frequency of a word phrase appearing within a text field in a PostgreSQL database.
I'm aware of functions such as to_tsquery() and I'm using it to check if a phrase exists within the text using to_tsquery('simple', 'sample text'), however, I'm unsure of how to count these occurrences accurately.
If the words are contained just once in the string (I am supposing here that your table contains two columns, one with an id and another with a text column called my_text):
SELECT
count(id)
FROM
my_table
WHERE
my_text ~* 'the_words_i_am_looking_for'
If the occurrences are more than one per field, this nested query can be used:
SELECT
id,
count(matches) as matches
FROM (
SELECT
id,
regexp_matches(my_text, 'the_words_i_am_looking_for', 'g') as matches
FROM
my_table
) t
GROUP BY 1
The syntax of this function and much more about string pattern matching can be found here.
I have the JSON column in my table which is having array's of dictionary. The array has standard format.
[{'path': 'chat/xyz.pdf', 'file_name': 'xyz.pdf'},
{'path': 'chat/xyl.pdf', 'file_name': 'xyl.pdf'}]
The table name is chat and column name is attachments. I want to perform search on file names such that even if i type one letter is typed then that row should be retrieved. For example: if i search by string 'pd' then all values with file_name having 'pd' string should be retrieved.
I tried this and it did work.
select distinct attachments from chat, jsonb_array_elements_text(attachments)
where value::json->>'file_name' like '%xyz%';
I took reference from documentation.
You can use an EXISTS condition, then you don't need the DISTINCT:
select c.*
from chat c
where exists (select *
from jsonb_array_elements(c.attachments) as t(doc)
where t.doc ->> 'file_name' like '%xyz%');
I'm trying to write a query in sql to exclude a keyword:
It's a list of cities written out (e.g. AnnArbor-MI). In the list there are duplicates because some have the word 'badsetup' after the city and these need to be discarded. How would I write something to exclude any city with 'badsetup' after it?
Your question title and content appear to be asking for two different things ...
Query cities while excluding the trailing 'badsetup':
SELECT regexp_matches(citycolumn, '(.*)badsetup')
FROM mytable;
Query cities that don't have the trailing 'badsetup':
SELECT citycolumn
FROM mytable
WHERE citycolumn NOT LIKE '%badsetup';
In psql, to select rows excluding those with the word 'badsetup' you can use the following:
SELECT * FROM table_name WHERE column NOT LIKE '%badsetup%';
In this case the '%' indicates that there can be any characters of any length in this space. So this query will find any instance of the phrase 'badsetup' in your column, regardless of the characters before or after it.
You can find more information in section 9.7.1 here: https://www.postgresql.org/docs/8.3/static/functions-matching.html
I have a SQL query, like so:
SELECT DISTINCT ID, Name FROM Table
This brings up all the distinct IDs (1...13), but in the 13 IDs, it repeats the name (as it comes up twice). The order of the query (ID, Name) has to be kept the same as the app using this query is coded with this assumption.
Is there a way to ensure there are no duplicates?
Thanks
You can try :
select id, name from table group by id,name
But it seems like distinct should work. Perhaps there are trailing spaces at the end of your name fields?
Instead of using DISTINCT, use GROUP BY
SELECT ID, Name FROM Table GROUP BY ID, Name
how to make this work in mysql?
select ID,COMPANY_NAME,contact1, SUBURB, CATEGORY, PHONE from Victoria where (city in ( select suburb from allsuburbs)) and CATEGORY='Banks'
this below statement is working:
select ID,COMPANY_NAME,contact1, SUBURB, CATEGORY, PHONE from Victoria where city in ( select suburb from allsuburbs)
if I add "and" , it gives me an empty resultset,
thanks
Learn how joins work.
select
v.ID,v.COMPANY_NAME,v.contact1,v.SUBURB,v.CATEGORY,v.PHONE
from
Victoria v
inner join allsuburbs s on s.suburb = v.city
where
v.CATEGORY='Banks'
Apart from that, your query does not make a whole lot of sense.
Your table is namend Victoria, but it contains a field named city?! Do your other cities have their own table too?
You have a table named allsuburbs, but your criterion is that Victoria.city equals allsuburbs.suburb, even though a field named Victoria.suburb exists?! What's Victoria.suburb for, then?
Your table is named allsuburbs. Do you have another table that contains suburbs or is this your only one? If it is your only one, the name is redundant.
You have a field contact1. Do you have contact2...contact10 as well? Bad database design.
Why is half of your fieldnames in caps, and not all of them (or none of them)?
Oh, and the usual format for SQL is: SQL keywords in caps, the field names etc. in mixed case/lower case. Much easier to read.
I think you might have misplaced a parentheses?
.. PHONE from Victoria where
(city in ( select suburb from allsuburbs)) and CATEGORY='Banks'
I'm guessing should be:
.. PHONE from Victoria where
city in ( select suburb from allsuburbs) and CATEGORY='Banks'
Not sure if that makes more sense, but the first case is not an ok SQL-statement I believe.