$ mysql -u root -p

mysql> SELECT USER FROM mysql.user;

mysql> SHOW DATABASES;

mysql> USE <database>;

mysql> SHOW TABLES;

mysql> SHOW COLUMNS FROM <table>;

The max length of varchar in MySQL is 64KB

VARCHAR(65535)

Lower with a multi-byte character set

VARCHAR(21844) CHARACTER SET utf8

mysql> SOURCE '/<path>/<to>/<file>.sql';

mysql> ALTER TABLE <table> ADD INDEX <index> (<column>);

mysql> SHOW INDEX FROM <table>;

mysql> ALTER TABLE <table> DROP INDEX <index>;

mysql> INSERT INTO <table> (field1, field2, field3) VALUES ('value1', 'value2','value3') ON DUPLICATE KEY UPDATE field1='value1', field2='value2', field3='value3';