I use PostgreSQL 13 on windows 10. I have a table with text-type columns. I'm looking for a query to find all the rows that contain just a single word is not accurate in a specific column.
Any ideas?
My table in database the form of, I try to extract all the rows with a single word.
output:
alvi
alexander
elmar
mahmoud
you can try this :
SELECT Name
FROM your_table
WHERE Name ~ '^\w+$'
see the power of the regular expressions in the manual
Related
I am converting the following T-SQL statement to Redshift. The purpose of the query is to convert a column in the table with a value containing a comma delimited string with up to 60 values into multiple rows with 1 value per row.
SELECT
id_1
, id_2
, value
into dbo.myResultsTable
FROM myTable
CROSS APPLY STRING_SPLIT([comma_delimited_string], ',')
WHERE [comma_delimited_string] is not null;
In SQL this processes 10 million records in just under 1 hour which is fine for my purposes. Obviously a direct conversation to Redshift isn't possible due to Redshift not having a Cross Apply or String Split functionality so I built a solution using the process detailed here (Redshift. Convert comma delimited values into rows) which utilizes split_part() to split the comma delimited string into multiple columns. Then another query that unions everything to get the final output into a single column. But the typical run takes over 6 hours to process the same amount of data.
I wasn't expecting to run into this issue just knowing the power difference between the machines. The SQL Server I was using for the comparison test was a simple server with 12 processors and 32 GB of RAM while the Redshift server is based on the dc1.8xlarge nodes (I don't know the total count). The instance is shared with other teams but when I look at the performance information there are plenty of available resources.
I'm relatively new to Redshift so I'm still assuming I'm not understanding something. But I have no idea what am I missing. Are there things I need to check to make sure the data is loaded in an optimal way (I'm not an adim so my ability to check this is limited)? Are there other Redshift query options that are better than the example I found? I've searched for other methods and optimizations but unless I start looking into Cross Joins, something I'd like to avoid (Plus when I tried to talk to the DBA's running the Redshift cluster about this option their response was a flat "No, can't do that.") I'm not even sure where to go at this point so any help would be much appreciated!
Thanks!
I've found a solution that works for me.
You need to do a JOIN on a number table, for which you can take any table as long as it has more rows that the numbers you need. You need to make sure the numbers are int by forcing the type. Using the funcion regexp_count on the column to be split for the ON statement to count the number of fields (delimiter +1), will generate a table with a row per repetition.
Then you use the split_part function on the column, and use the number.num column to extract for each of the rows a different part of the text.
SELECT comma_delimited_string, numbers.num, REGEXP_COUNT(comma_delimited_string , ',')+1 AS nfields, SPLIT_PART(comma_delimited_string, ',', numbers.num) AS field
FROM mytable
JOIN
(
select
(row_number() over (order by 1))::int as num
from
mytable
limit 15 --max num of fields
) as numbers
ON numbers.num <= regexp_count(comma_delimited_string , ',') + 1
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 need to use Full Text Search with Postgresql but I don't find the way to look for a list of words from a table (using ts_query) against an indexed text field (ts_vector data type). Is ts_query just able to process a few words or can process also multiple values that come from a table?
Thanks in advance for your help.
Let me try to formulate an answer according to the comments given on the question (if I understand your request correctly).
Problem
You are trying to do a full text search on the table tableA, column indexed_text_field (a tsvector type) based on words that are stored as text in another table tableB in a column called words.
Solution
First, if you wish to feed PostgreSQL multiple tokens (individual words) during a full text search you have two functions at your disposal:
to_tsquery()
plainto_tsquery()
In the first function you need to split each given token with an ampersand (&). The second function can be fed any string of text and it will chop it into tokens for you. More info here.
Your challenge is that you wish to select matches based on words present in another table. This can be done in different ways, for example via a simple (INNER) JOIN:
SELECT a.* FROM tableA a, tableB b WHERE a.indexed_text_field ## to_tsquery(b.words);
Or if you have multiple words in the words column you should most likely be using the plainto_tsquery() function to keep things simple:
SELECT a.* FROM tableA a, tableB b WHERE a.indexed_text_field ## plainto_tsquery(b.words);
Yet, if you must use the more low-level to_tsquery() version:
SELECT a.* FROM tableA a, tableB b WHERE a.indexed_text_field ## to_tsquery(replace(b.words, ' ', '&'));
In the latter you replace all spaces between the words with and ampersand, thus making them separate tokens. Mind the index usage on the last one though, as you might need to create an expression index on the usage of the replace() function.
I am using mysql workbench (SQL Editor). I need copy the list of columns in each query as was existed in Mysql Query Browser.
For example
Select * From tb
I want have the list of fields like as:
id,title,keyno,......
You mean you want to be able to get one or more columns for a specified table?
1st way
Do SHOW COLUMNS FROM your_table_name and from there on depending on what you want have some basic filtering added by specifying you want only columns that data type is int, default value is null etc e.g. SHOW COLUMNS FROM your_table_name WHERE type='mediumint(8)' ANDnull='yes'
2nd way
This way is a bit more flexible and powerful as you can combine many tables and other properties kept in MySQL's INFORMATION_SCHEMA internal db that has records of all db columns, tables etc. Using the query below as it is and setting TABLE_NAME to the table you want to find the columns for
SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='your_table_name';
To limit the number of matched columns down to a specific database add AND TABLE_SCHEMA='your_db_name' at the end of the query
Also, to have the column names appear not in multiple rows but in a single row as a comma separated list you can use GROUP_CONCAT(COLUMN_NAME,',') instead of only COLUMN_NAME
To select all columns in select statement, please go to SCHEMAS menu and right click ok table which you want to select column names, then select "Copy to Clipboard > Select All statement".
The solution accepted is fine, but it is limited to field names in tables. To handle arbitrary queries would be to standardize your select clause to be able to use regex to strip out only the column aliases. I format my select clause as "1 row per element" so
Select 1 + 1 as Col1, 1 + 2 Col2 From Table
becomes
Select 1 + 1 as Col1
, 1 + 2 Col2
From Table
Then I use simple regex on the "1 row per select element" version to replace "^.* " (excluding quotes) with nothing. The regex finds everything before the final space in the line, so it assumes your column aliases doesn't contain spaces (so replace spaces with underscore). Or if you don't like "1 row per element" then always use "as" keyword to give you a handle that regex can grasp.
i know that in Oracle you can select rows by symbols that contains in a column value, like :
select * from table where id in (select id from table where name like '%asd%')
But i need to select values from database that contains characters like ā,ē,č,ž etc, by a,e,c,z. is it possible in Oracle, and if it is than how ?
i also know :
regexp_like(column,'asd|asc|ase|eqw')
but there can be word like šķūņu , and when user write for search skunku, than i need to write in regexp all kind of combinations of symbols ā,ķ,ū,ņ... it`s a bad option for me...
I have solved my problem this way :
Replace(Convert(decompose(signal_custom_fields.field_value),'US7ASCII'),'?') like '%Riga%'
i decompose all characters with ā, than i convert decomposed symbole to ?, and remoove it from the word, and than i compair entered word with all data in data base. is there another way to do it ?