SQL Format Notes

This content mainly introduces the basic SQL statements for creating, modifying, and deleting tables, as well as data querying, inserting, updating, and deleting. First, when creating a table, you need to define the data types and constraints of columns; for modifying a table, you can add or delete columns/constraints, or change the properties of columns; for deletion, you can directly use the `drop table` command and optionally cascade delete related dependencies. Query statements use the `select` keyword to retrieve data from specified tables and support grouping and sorting. In addition, various conditional expressions are also introduced, such as `like`, `insert into...value` (note: the original text may have an incomplete `insert into...value` statement, which has been retained as is).