SQL commands are grouped into four major categories depending on their functionality: Data Definition Language (DDL) – These SQL commands are used for creating, modifying, and dropping the structure of database objects. The commands are CREATE, ALTER, DROP, RENAME, and TRUNCATE.Click to see full answer. Also to know is, what are DDL commands in SQL?DDL(Data Definition Language) : DDL or Data Definition Language actually consists of the SQL commands that can be used to define the database schema. It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in the database.Beside above, what is a * in SQL? In SQL * means All record, not only in SQL in other programming languages * is called as wild card character which means all present record. In SQL we use * with SELECT query to select all records forma desired table. Query Statement: SELECT * FROM `table name`; that will output all the record in the given table. Consequently, what is the most common SQL command? FROM … is the most basic and commonly used query in SQL. It’s used for retrieving data from a table.What is foreign key in DBMS?A foreign key is a column or group of columns in a relational database table that provides a link between data in two tables. The concept of referential integrity is derived from foreign key theory. Foreign keys and their implementation are more complex than primary keys.