I havea table with a string column:
text
I have two cars
I have a big house
I want to query from this table only records that has the word cars
the expected output:
I have two cars
I tried:
select text from tlb
where text in ('cars')
but it only returns exactly 'cars'
Postgresql V14
LIKE operator could help.
select * from tlb where lower(texts) like '%cars%';
Related
I'm having trouble creating a query for the following task: i want to return exactly one row with columns: region_id, region_name, province_name, province_code, country_name, country_code for any given regionid. The database has 3 tables "countrylist" , "provinces" and "regionlist"
the table countrylist has the following columns : countryid, language code, countryname, countrycode and continentid
provinces : country_code, country_name, province_code, province_name
regionlist: regionid, regiontype.
So I tried writing a query for joining the table but I'm sure if I'm doing it correct.
exactly one row with columns: region_id, region_name, province_name, province_code, country_name, country_code for any given regionid.
I am not 100% aware of the differences between Postgres and MySQL - but guess you get the idea at the very least.
One way to do it, to get your id with WHERE regionlist.regionid = and join the other tables. From either the regionlist you can use the LIMIT (reference) to get a limited amount of rows.
Apparently neither provinces nor country have a common column with regionlist, so I can not tell where the link between those are. However, once you have 1 row of the region list you should have no troubles joining them with the others (if the links are trivial).
I have a table contains columns 'employeename' and 'id', how can I sort the 'employeename' column following alphabetical order of the names initial?
Say the table is like this now:
employeename rid eid
Dave 1 1
Ben 4 2
Chloe 6 6
I tried the command ORDER BY, it shows what I want but when I query the data again by SELECT, the showed table data is the same as original, indicting ORDER BY does not modify the data, is this correct?
SELECT *
FROM employee
ORDER BY employeename ASC;
I expect the table data to be modified (sorted by names alphabetical order) like this:
employeename rid eid
Ben 4 2
Chloe 6 6
Dave 1 1
the showed table data is the same as original, indicting ORDER BY does not modify the data, is this correct?
Yes, this is correct. A SELECT statement does not change the data in a table. Only UPDATE, DELETE, INSERT or TRUNCATE statements will change the data.
However, your question shows a misconception on how a relational database works.
Rows in a table (of a relational database) are not sorted in any way. You can picture them as balls in a basket.
If you want to display data in a specific sort order, the only (really: the only) way to do that is to use an ORDER BY in your SELECT statement. There is no alternative to that.
Postgres allows to define a VIEW that includes an ORDER BY which might be an acceptable workaround for you:
CREATE VIEW sorted_employee;
AS
SELECT *
FROM employee
ORDER BY employeename ASC;
Then you can simply use
select *
from sorted_employees;
But be aware of the drawbacks. If you run select * from sorted_employees order by id then the data will be sorted twice. Postgres is not smart enough to remove the (useless) order by from the view's definition.
Some related questions:
Default row order in SELECT query - SQL Server 2008 vs SQL 2012
What is the default SQL result sort order with 'select *'?
Is PostgreSQL order fully guaranteed if sorting on a non-unique attribute?
Why do results from a SQL query not come back in the order I expect?
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 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 am using a PostgreSQL database. I have one select query:
select userid, name, age from tbluser;
Now there is another table, tblcalculatedtax, which is generated on the fly and their column names are not predefined, the only mapping between that table and this table is userid. I want to get records after joining two tables. How can I get that?
Simpler:
SELECT *
FROM tbluser
JOIN tblcalculatedtax USING (userid)
Details in the fine manual about SELECT.
Your need SQL Joins. Here's a W3Schools tutorial: http://www.w3schools.com/sql/sql_join.asp
To quickly answer your question, though:
SELECT * FROM tbluser
INNER JOIN tblcalculatedtax
ON tbluser.userid=tblcalculatedtext.userid
The * selects all the columns, so you don't need to know their names. Of course, I'm not sure what use a column is to you if you don't know it's name: do you know what data it contains?