0
votes
1answer
30 views

What's the difference between INSERT … SELECT and SELECT INTO

Let's say I have a table item and an other one versionned_item. From time to time, I want to copy data from item to versionned_item. What I did is WITH subset AS (SELECT ...) INSERT INTO ...
3
votes
5answers
95 views

Find all values not present for other values of other column

Let's suppose I have a table with integer columns a and b (each pair (a,b) is unique) and following data: a | b ------- 1 | 2 1 | 3 1 | 4 1 | 5 2 | 1 2 | 3 2 | 4 3 | 1 3 | 3 Now I need to ...
0
votes
1answer
17 views

PostgreSQL SQL syntax - JOIN and substrings

I have a single table of hostnames and NFS exports, some but not all of which are related. Example entries: HOST VOLUME ----- ---------- host1 vol1 host1 vol2 host1 ...
0
votes
1answer
29 views

How do I select the value with SERIAL data type in postgres

I wanna ask how to select coloum that has SERIAL data type. I already try to do that but the output is like this 'Resource id #3', and not just '3' I use SERIAL so I dont have to input ID like when ...
0
votes
1answer
30 views

Selecting 3MB (or more/less) data from database server

I installed PostgreSQL Server on my Windows 7 machine. I created database and a simple table, and populated the table. Now I want to connect through the network with my Postgres server and select a ...
1
vote
1answer
54 views

PostgreSQL WHERE clause with two OR'ed conditions, priority to first

I'm storing user data (username, email, password hash) in PostgreSQL, and I can only enforce uniqueness on username. I'd like to let users provide either their username or their email when they login. ...
0
votes
1answer
381 views

Postgres: How to insert row with autoincrement id

There is a Table "context". There is an autoincrement id "context_id". I am using sequence to retrieve the next value. SELECT nextval('context_context_id_seq') The result is: 1, 2, 3,...20.... But ...
0
votes
1answer
68 views

ORDER BY that doesn't contain repeating values

Relevant SQL Fiddle (postgres 9.2) How do I state a SELECT .. ORDER BY .. that avoids having repeated values for a column? That is, for rows of the column "rank" (1,3,3,1) how do I get a result so ...
1
vote
2answers
127 views

How to delete rows from a table when we're joining and return data?

I have two queries: The first one is as below: SELECT * FROM batch bp INNER JOIN sender_log sl ON sl.id=bp.log_id AND bp.protocol='someprotocol' The second query is used to delete rows: ...
4
votes
2answers
118 views

select specified number of unique IDs where second column is unique

Look at the following example starting from the top row (id=9) and work your way down, selecting a limit of 4 rows that have sec's that we have not yet seen. We "select" id=9 because we don't yet have ...
3
votes
1answer
95 views

postgres filtering select based on combination of joins

I am having trouble filtering a request that depends on a combination of child elements (one-to-many relationship) Please consider the following example. CREATE TABLE sample_container ( id serial ...
1
vote
3answers
1k views

Select query to retrieve values even if are null

I need some help in a query. Need to retrieve data from 1 table, even if one of the field has null value. Here's an example: Select name, SUM(credit) as credit From expenses Where name like ...
2
votes
3answers
416 views

How to query efficiently from Postgres to select special words?

Let's say that I have a table called words with very many records. Columns are id and name. In the words table I have for example: 'systematic', 'سلام','gear','synthesis','mysterious', etc. NB: ...
1
vote
1answer
556 views

Select next and previous rows

I have the following table: CREATE TABLE post ( id bigint primary key, thread_id bigint, is_notice boolean, title text, content text ) I display the list ...
2
votes
2answers
78 views

Get count of processed queries

I have been searching a while to find a way to retrieve the amount of queries my postgres database is processing and responding to. I found various statistics about disk I/O, insert/update statistics ...
2
votes
1answer
886 views

Postgres nested hstore select query

I have a carts table with items hstore column. An example entry in this column is: carts.items row#1 = { "1614" => {:quantity=>"100", :price_cents=>1655}, ...
0
votes
1answer
1k views

How to create an Sql table from SELECT with a multiple row DISTINCT constraint?

I want to create a table from a SELECT statement based on a multiple row DISTINCT, but PostgreSQL does not allow me to do it. I need to create a table where the elements were previously selected from ...
2
votes
1answer
1k views

To select from all tables inside the schema in PostgreSQL

Is it possible to select from all tables inside the schema? I got all the table names from select table_name from information_schema.tables but I am unable to use it to do my query.
2
votes
1answer
88 views

How to select nodes where all children is satisfied?

I have a tree structure of light bulbs. I want to turn on all the light bulbs starting from the leafs of the tree. A light bulb cannot be turned on unless all its immediate children are turned on. ...
2
votes
3answers
6k views

Getting SELECT to return a constant value even if zero rows match

Consider this select statement: SELECT *, 1 AS query_id FROM players WHERE username='foobar'; It returns the column query_id with value 1 along with a player's other columns. How would ...
1
vote
1answer
2k views

Error “column does not exist” in a SELECT with JOIN and GROUP BY query

I'm using PostgreSQL 9.1 with a Ruby on Rails application. I'm trying to list the last version of each "charge" (in my history table : hist_version_charges) belonging to the same project id ...
3
votes
1answer
75 views

PostgresSQL: Get single attribute of UDT in SELECT statement

I created a user-defined type in a PostgreSQL 9.2 database and am trying in the SELECT statement to get only an attribute of the UDT. However, I don't seem to get my code to work. Creation of type ...
4
votes
1answer
237 views

Does the order of fields in SELECT query matter when using composite indexing?

I understand that the order of columns in the index itself matters immensely; however, what about the order of columns in the subsequent SELECT queries that make use of that index? For example, if I ...
0
votes
1answer
463 views

Retrieving a fixed range of rows from Postgresql

I have a query: select qid,ansid,ans from table1 where askerid='something' This query can retrieve many rows. But I want to display only 50 rows at a time and then if the user clicks on more, the ...
2
votes
1answer
342 views

Select consecutive number of rows starting from some number

What I need is to select 100 consecutive rows from a table, starting at some defined point without ordering data. As far as I can observe, inserted data to a table is stored in no order but is ...
3
votes
1answer
455 views

Tricky selection of grouped rows, selecting based on values of two distinct but related rows

Say I have a table with the following information (sorted here for display purposes) taskid | reference | centreid | date_out --------------------------------------------------- 10001 | ...
2
votes
2answers
947 views

Select rows with repeat data within certain timeframe

As a follow-up question to my previous question on difficult row categorisation, I have another problem which I'm sure will be easily solvable. After this I plan on reading a good book or two on ...
22
votes
1answer
3k views

USING construct in JOIN clause can introduce optimization barriers in certain cases?

It was brought to my attention that the USING construct (instead of ON) in the FROM clause of SELECT queries might introduce optimization barriers in certain cases. I mean this key word: SELECT * ...
7
votes
5answers
12k views

How can I use a default value in a Select query in PostgreSQL?

I would like to use a default value for a column that should be used if no rows is returned. Is that possible in PostgreSQL? How can I do it? Or is there any other way I can solve this? E.g. ...