android problem solve

Volley Apache Error

<application
        android:usesCleartextTraffic="true"
        >
        <uses-library
            android:name="org.apache.http.legacy"
            android:required="false" />

DexArchiveMergerException

android {

    compileSdkVersion 26

    defaultConfig {

        applicationId "com.example.equal07.firebasetest"

        minSdkVersion 15

        targetSdkVersion 26

        multiDexEnabled true

        versionCode 1

        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }

MariaDB(MySQL)

Install MariaDB

$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get install mysql-server mysql-client

Connection to DB(initial)

$ sudo mysql -u root #initially connection available

mysql> USE mysql;
mysql> SELECT User, Host, plugin FROM mysql.user;

+------------------+-----------------------+
| User             | plugin                |
+------------------+-----------------------+
| root             | auth_socket           |
| mysql.sys        | mysql_native_password |
| debian-sys-maint | mysql_native_password |
+------------------+-----------------------+

The plugin for root should be changed to mysql_native_password for logging in.

mysql> update user set plugin='mysql_native_password' where user='root';
mysql> flush privileges;
mysql> select user, host, plugin from user;

ChangePassword

mysql> update user set password=password('1234') where user='root';

mysql> flush privileges;

Connection to DB with Password

$ sudo mysql -u root -p

External connection

$ cd /etc/mysql/mariadb.conf.d

$ sudo nano 50-server.cnf

change bind-address = 127.0.0.1 to #bind-address = 127.0.0.1

$ sudo service mysql restart

Permission external connection

mysql> grant all privileges on *.* to 'root'@'%' identified by ' PASSWORD'

Etc. command

$ sudo service mysql start

$ sudo service mysql stop
$ sudo service mysql restart

MySQL Command

mysql> show databases;
mysql> create database DBNAME;
mysql> drop database DBNAME;

mysql> use DBNAME;
mysql> show tables;

mysql> create table TABLENAME(COL1 TYPE1, COL2 TYPE2, .... );
mysql> desc TABLENAME;

mysql> alter table TABLENAME add COL1 type1;
mysql> alter table TABLENAME drop COL1;
mysql> alter table TABLENAME change column OLDCOL NEWCOL TYPE;
mysql> alter table TABLENAME modify column COL NEWTYPE;
mysql> alter table TABLENAME  rename NEWTABLENAME;
mysql> drop table TABLENAME;
mysql> insert into TABLENAME values('VALUE', 'VALUE',...);
mysql> insert into TABLENAME (COL1, COL2) values ('VALUE1','VALUE2');

mysql> select * from TABLENAME;
mysql> select * from TABLENAME where COND1 and/or COND2...;
mysql> select attr1, attr2,... from TABLENAME (where COND);

mysql> update TABLENAME set COL1='VALUE1',COL2='VALUE2',... where  COND;
mysql> delete from TABLENAME where COL1='VALUE1' and/or COL2='VALUE2'....;
mysql> truncate TABLENAME;

mysql> insert into mysql.user(host,user,password,ssl_cipher,x509_issuer,x509_subject,authentication_string)
values ('localhost','ID',password('PASSWORD'),"","","","");

PERMISSION
mysql> insert into mysql.db values('HOSTNAME','DBNAME','ID','y','y','y','y','y','y','y','y','y','y','y','y','y','y','y','y','y','y','y');

mysql> grant all privileges on DBNAME.TABLENAME(or *) to 'ID'@'HOSTNAME' identified by 'PASSWORD';

mysql> grant all privileges on *.* to 'ID'@'HOSTNAME' identified by 'PASSWORD';

mysql> flush privileges;

mysql> update user set password=password('NEWPASSWORD') where user='ID';