A .SQL (Structured Query Language)
1.sql role of the client to communicate with a database server
Two .SQL statement classification
1.DDL: database definition language for defining database objects, such as: databases, tables, columns, etc.
2.DML: database manipulation language, used to define the database record, the recording table is updated (additions and deletions)
3.DCL: Database control language used to define access rights and security levels
4.DML: database query language used to query records (in fact, part of DML DML, but are separated)