sudo service mariadb start

$> ps -ef | grep mysql
dean     12960  5439  0 11:50 ?        00:00:00 /bin/sh /usr/bin/mysqld_safe
dean     13049 12960  0 11:50 ?        00:00:00 /usr/sbin/mariadbd --basedir=/usr --datadir=/home/dean/data/mysql/ --plugin-dir=/usr/lib/mysql/plugin --log-error=/home/dean/logs/mysql/mysql.log --pid-file=DESKTOP-9P4ULB5.pid --socket=/var/lib/mysql/mysql.sock --port=3333

$> mysql --socket=/var/lib/mysql/mysql.sock
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 3
Server version: 10.5.16-MariaDB-1:10.5.16+maria~bullseye mariadb.org binary distribution

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]>

This is how mariadb strats up. Always try to check error log first, and try to ping down from the following places:

/etc/init.d/mariadb calls /usr/bin/mysqld_safe and it uses user config /home/dean/.my.cnf

$> cat /home/dean/.my.cnf

[client-server]
port=3333

[mariadb]
user=dean
datadir=/home/dean/data/mysql/
socket=/var/lib/mysql/mysql.sock
log-error=/home/dean/logs/mysql/mysql.log

$> /etc/init.d/mariadb start Starting MariaDB database server: mariadbdinstall: cannot change owner and permissions of ‘/run/mysqld’: No such file or directory The fix is simply: $> sudo mkdir /run/mysqld

You will need to chmod -R 777 /var/lib/mysql

A lot of ideas from: https://falseisnotnull.wordpress.com/2013/06/23/mariadbs-sequence-storage-engine/ The sequence engine is particularly useful with joins and subqueries. For example, this query finds all prime numbers below 50: MariaDB [test]> SELECT seq FROM seq_2_to_50 s1 WHERE 0 NOT IN (SELECT s1.seq % s2.seq FROM seq_2_to_50 s2 WHERE s2.seq <= sqrt(s1.seq)); +-----+ | seq | +-----+ | 2 | | 3 | | 5 | | 7 | | 11 | | 13 | | 17 | | 19 | | 23 | | 29 | | 31 | | 37 | | 41 | | 43 | | 47 | +-----+ 15 rows in set (0.000 sec)

And almost (without 2, the only even prime number) the same result with joins: MariaDB [test]> SELECT s1.seq FROM seq_2_to_50 s1 JOIN seq_2_to_50 s2 -> WHERE s1.seq > s2.seq AND s1.seq % s2.seq <> 0 -> GROUP BY s1.seq HAVING s1.seq - COUNT(*) = 2; +-----+ | seq | +-----+ | 3 | | 5 | | 7 | | 11 | | 13 | | 17 | | 19 | | 23 | | 29 | | 31 | | 37 | | 41 | | 43 | | 47 | +-----+ 14 rows in set (0.002 sec)

Find multiples of both 3 and 5 SELECT s1.seq FROM seq_5_to_100_step_5 s1 INNER JOIN seq_3_to_100_step_3 s2 ON s1.seq = s2.seq;

Sequence of 1-char strings SELECT CHAR(seq) AS ch FROM ( -- lowercase (SELECT seq FROM seq_97_to_122 l) UNION -- uppercase (SELECT seq FROM seq_65_to_90 u) UNION -- digits (SELECT seq FROM seq_48_to_57 d) ) ch; Sequence of hours, halfes of an hour, etc -- Hours in a day SELECT CAST('00:00:00' AS TIME) + INTERVAL (s.seq - 1) HOUR AS t FROM (SELECT seq FROM seq_1_to_24) s; -- Halfes of an hour in a day SELECT CAST('00:00:00' AS TIME) + INTERVAL (30 * s.seq) MINUTE AS t FROM (SELECT seq FROM seq_1_to_48) s;

Sequence tables can also be useful in date calculations. MariaDB [test]> SELECT DAYNAME('1980-12-05' + INTERVAL (seq) YEAR) day, '1980-12-05' + INTERVAL (seq) YEAR date FROM seq_0_to_10; +-----------+------------+ | day | date | +-----------+------------+ | Friday | 1980-12-05 | | Saturday | 1981-12-05 | | Sunday | 1982-12-05 | | Monday | 1983-12-05 | | Wednesday | 1984-12-05 | | Thursday | 1985-12-05 | | Friday | 1986-12-05 | | Saturday | 1987-12-05 | | Monday | 1988-12-05 | | Tuesday | 1989-12-05 | | Wednesday | 1990-12-05 | +-----------+------------+ 11 rows in set (0.000 sec)

Ref: https://github.com/bobsense/mysql-arm64/blob/ba4110f6af182331eda2aad8fa4fd4069729515b/percona-server-5.6.22-72.0/mysql-test/t/select_found.test

    create or replace table t1 (a int not null auto_increment, b int not null, primary key(a));
    insert into t1 (b) values (2),(3),(5),(5),(5),(6),(7),(9);
    select SQL_CALC_FOUND_ROWS * from t1;
    select found_rows();  -- 8
    select SQL_CALC_FOUND_ROWS * from t1 limit 1; -- Assume you used limit and got the answer
    -- with SQL_CALC_FOUND_ROWS and FOUND_ROWS you can get the total with running the query without the limit again
    select found_rows();  -- 8    
    select SQL_BUFFER_RESULT SQL_CALC_FOUND_ROWS * from t1 limit 1;
    select found_rows();  -- 8
    select SQL_CALC_FOUND_ROWS * from t1 order by b desc limit 1;
    select found_rows();  -- 8
    select SQL_CALC_FOUND_ROWS distinct b from t1 limit 1;
    select found_rows();  -- 6
    select SQL_CALC_FOUND_ROWS b,count(*) as c from t1 group by b order by c desc limit 1;
    select found_rows();  -- 6
    select SQL_CALC_FOUND_ROWS * from t1 left join t1 as t2 on (t1.b=t2.a) limit 2,1;
    select found_rows();  -- 8
    drop table t1;

insert into t1 (b) values (2),(3),(5),(5),(5),(6),(7),(9); select * from t1; select found_rows();