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List all sequences in a Postgres db 8.1 with SQL
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The following query gives names of all sequences.
SELECT c.relname FROM pg_class c WHERE c.relkind = 'S';
Typically a sequence is named as ${table}_id_seq. Simple regex pattern matching will give you the table name.
To get last value of a sequence use the following query:...
PostgreSQL DISTINCT ON with different ORDER BY
...llowing approaches:
The general solution that should work in most DBMSs:
SELECT t1.* FROM purchases t1
JOIN (
SELECT address_id, max(purchased_at) max_purchased_at
FROM purchases
WHERE product_id = 1
GROUP BY address_id
) t2
ON t1.address_id = t2.address_id AND t1.purchased_at = t2...
Semicolon before self-invoking function? [duplicate]
...eventing the ui tabs from working properly.
The error message was Invalid character in jquery.all.ui.js Line: 1. Char: 1.
I stumbled on the semi-colon completely by chance.
When I removed the ; from the ;(function($) it worked, seemingly without side-effects or loss of functionality.
I am using ...
How do I do top 1 in Oracle?
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If you want just a first selected row, you can:
select fname from MyTbl where rownum = 1
You can also use analytic functions to order and take the top x:
select max(fname) over (rank() order by some_factor) from MyTbl
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Replace one substring for another string in shell script
...easily breaks on any nontrivial input string (irregular spacing, shell metacharacters, etc).
– tripleee
Jul 17 '18 at 16:54
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Flatten an irregular list of lists
...s it fails with the cycle.. i think because a string is also an "array"-of-chars
– sten
Mar 20 '18 at 20:16
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Get record counts for all tables in MySQL database
...get the count of rows in all tables in a MySQL database without running a SELECT count() on each table?
19 Answers
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MySQL “WITH” clause
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You might be interested in somethinkg like this:
select * from (
select * from table
) as Subquery
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COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
how to exclude null values in array_agg like in string_agg using postgres?
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SQL Fiddle
select
id,
(select array_agg(a) from unnest(canonical_users) a where a is not null) canonical_users,
(select array_agg(a) from unnest(non_canonical_users) a where a is not null) non_canonical_users
from (
SELE...