In the past, we commonly used commands
show databases
show tables
show processlist,
in fact, these are all from information_schema. When I started to understand information_schema, I found that so many interesting data have been saved by it. Familiarity with this library is very helpful for understanding mysql.
The table in information_schema holds various database information. I think the tables in this library are very useful.
View engine
information_schema.ENGINS corresponds to show engines;
View database
information_schema.SCHEMATA corresponds to show databases;
View table
information_schema.TABLES corresponds to show tables;
View column
information_schema.COLUMNS corresponds to show columns from table_name
View index
information_schema.STATISTICS corresponds to show index from table_name
View thread
information_schema.PROCESSLIST Show processlist with business
There are other tables in information_schema such as VIEWS, TRIGGERS, etc.
Several questions about mysql infomation_schema. The relationship between table_row in tables and the actual number of rows
There is no difference between begin vs start transaction, you can understand it as an alias, the role is to start a transaction.