Database

To get database table columns names of a mysql database you can use "DESCRIBE my_table;" method.

To update a table you must create a custom module. Example , Here we use mymodule.

Move some tables into another database.

Example:

Get Database Schema

$schema = \Drupal\Core\Database\Database::getConnection()->schema();

Entity Field types, Data types

(BaseFieldDefinition::create types)

Repair all tables
mysqlcheck -u root -p --auto-repair --check --all-databases

Repair a database
mysqlcheck -u root -p  --repair --databases databasesname

Check a database
mysqlcheck -u root -p --databases databasesname

If there no data, You can use field_update_field (tested on D7) Like:

Show all columns of a table.

Syntax: SHOW COLUMNS FROM the_table_name;
Example: Show all columns of the mysql user table.
mysql> SHOW COLUMNS FROM mysql.user;

Export Drupal 8 MySQL Database via Drush

drush cr
drush sql-dump > /pathto/mysql-dump-drupal8.sql

Import Drupal 8 and MySQL Database via Drush

drush sql-drop
drush sql-cli
mysql> source /pathto/mysql-dump-drupal8.sql

The database settings (and connection) has 3 levels.

1. KEY
2. TARGET
3. DATA

Example:

$databases[KEY][TARGET] = array (
 DATA
);

Like: