<<TableOfContents(2)>>

= MySQL =

== Connect mysql host ==
{{{#!highlight bash
mysql -h localhost -u userx dbx -ppasswordx
mysql -h localhost -u userx dbx -p # asks for password later
}}}

== Dynamic SQL , conditional where ==
{{{#!highlight sql
SELECT first_name, last_name, subsidiary_id, employee_id
  FROM employees
 WHERE ( subsidiary_id    = :sub_id OR :sub_id IS NULL )
   AND ( employee_id      = :emp_id OR :emp_id IS NULL )
   AND ( UPPER(last_name) = :name   OR :name   IS NULL )


select * from mysql.user
where (user=NULL or NULL is null) 
and (host=NULL or NULL is null)

select * from mysql.user
where (user='root' or 'root' is null) 
and (host=NULL or NULL is null)

select * from mysql.user
where (user='root' or 'root' is null) 
and (host='127.0.0.1' or '127.0.0.1' is null)
}}}

== MySql workbench Slackware64 14.1 ==
{{{#!highlight bash
wget http://dev.mysql.com/get/Downloads/MySQLGUITools/mysql-workbench-community-6.1.7-1.el6.x86_64.rpm
cp ~/Downloads/mysql-workbench-community-6.1.7-1.el6.x86_64.rpm /tmp
cd /tmp
rpm2tgz mysql-workbench-community-6.1.7-1.el6.x86_64.rpm
installpkg mysql-workbench-community-6.1.7-1.el6.x86_64.tgz 
}}}

== mysqldump - backup database ==
{{{#!highlight bash
mysqldump -h hostx -u userx -ppassx dbname > /tmp/dump.sql
mysqldump -h 127.0.0.1 -u userx -ppass -P 3306 --ssl db_exampleDB > backup_exampleDB_20210524.sql
# restore DB 
mysql -h 127.0.0.1 -u root -p???????? mysql < dump.sql
}}}

== Error MariaDB 5.5 mysqldump ==
 * mysqldump: Couldn't execute 'SET OPTION SQL_QUOTE_SHOW_CREATE=1': Unknown system variable 'OPTION' (1193)
 * cp /usr/bin/mysqldump /tmp/msd
 * vim /tmp/msd
 * Escape, 
 * /SET OPTION
 * R
 * replace option with spaces
 * Escape
 * :wq

Use /tmp/msd -h hostx -u userx -ppassx dbname > /tmp/dump.sql

== Show users ==
{{{#!highlight sql
select host,user,password from mysql.user;
}}}

== Create function ==
{{{#!highlight sql
DELIMITER $$
DROP FUNCTION IF EXISTS hello;
CREATE FUNCTION hello() RETURNS TEXT LANGUAGE SQL
BEGIN
  RETURN 'Hello';
END;
$$
DELIMITER ;
-- test function
select hello();
set sql_mode='ansi';
show create function hello;
}}}

== User creation and grants to select and execute function ==
{{{#!highlight sql
create user 'userx'@'%' identified by 'passwordx';
grant select on dbx.tablex to 'userx'@'%';
grant execute on function dbx.hello to 'userx'@'%';
}}}

== Most used commands ==
{{{#!highlight sql
help contents;
help show;
help create;
show databases;
use mysql; -- select database
show tables;
desc user; -- describe table user
set sql_mode=ansi; -- set sql mode to ansi
show create table user; -- show DDL to create table user
show grants; -- show grants for current user
show privileges; -- show privileges to be used in grants
}}}

== Trigger before insert to generate unique id ==
{{{#!highlight sql
CREATE TRIGGER T_BEFORE_INSERT_TABLEX 
BEFORE UPDATE ON dbx.TABLEX 
FOR EACH ROW SET NEW.UUID = uuid() ;
}}}

== Install on CentOS 6.6 ==
{{{#!highlight bash
yum install mysql
yum install mysql-server
service mysqld start
mysql
create user 'userx'@'%' identified by 'passwordx';
create user 'userx'@'localhost' identified by 'passwordx';
grant all on test.* to  'userx'@'%';
grant all on test.* to  'userx'@'localhost';
show grants for 'userx'@'%';
show grants for 'userx'@'localhost';
}}}

== Create test table ==
{{{#!highlight sql
CREATE TABLE MyGuests ( id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY, firstname VARCHAR(30) NOT NULL, lastname VARCHAR(30) NOT NULL, email VARCHAR(50), reg_date TIMESTAMP )
insert into MyGuests (firstname,lastname,email,reg_date) values('AA','BB','xyz@test.com','2015-02-13T00:00:00');
insert into MyGuests (firstname,lastname,email,reg_date) values('CC','DD','aaaaxyz@test.com','2015-02-13T14:00:00');
select * from MyGuests;
}}}

== Install MariaDB debian buster ==
=== Install ===
{{{#!highlight bash
apt-get update
apt install mariadb-server
mysql_secure_installation
# define root pass
su
mysql
GRANT ALL ON *.* TO 'admin'@'localhost' IDENTIFIED BY '????????' WITH GRANT OPTION;
FLUSH PRIVILEGES;
create database testdb;
show databases;
exit
}}}

=== SpringBoot JPA application.properties ===
{{{
spring.datasource.url=jdbc:mariadb://localhost:3306/testdb
spring.datasource.driverClassName=org.mariadb.jdbc.Driver
spring.datasource.username=admin
spring.datasource.password=????????
spring.jpa.database-platform=org.hibernate.dialect.MariaDBDialect
spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.show-sql=true
}}}

=== pom.xml ===
{{{#!highlight xml
<dependency>
	<groupId>org.mariadb.jdbc</groupId>
	<artifactId>mariadb-java-client</artifactId>
	<version>1.4.4</version>
</dependency>
}}}

== Create view ==
{{{#!highlight sql
create or replace view v_test as 
  select fielda, fieldb  
  from v_test2 where fieldId = tablex.fieldId
  union
  select fielda, fieldb  
  from v_test3 where fieldId = tablez.fieldId;
}}}

== Explain ==
 * https://dev.mysql.com/doc/refman/8.0/en/table-scan-avoidance.html
The output from EXPLAIN shows ALL in the type column when MySQL uses a full table scan to resolve a query.
{{{#!highlight sql
explain select * from tablex;
}}}
== Current date ==
{{{#!highlight sql
select DATE_FORMAT(NOW(),'%Y-%m-%dT%TZ');
}}}