Q.What is SQL? Explain the difference between DDL and DML, giving two commands of each.

SQL is the language of relational databases, and its commands are grouped by the job they do; this question asks for the two most important groups.

SQL (Structured Query Language) is the standard language used to create and work with data in a relational database such as MySQL. Instead of writing a full program, you write short SQL statements that tell the DBMS what you want; MySQL follows the ANSI SQL-99 standard. SQL commands are grouped into sub-languages according to their job. The two most important are DDL and DML.

DDL (Data Definition Language) — commands that define or change the structure of the database and its tables. They build and alter the 'containers' that hold data.

• Example commands: CREATE (make a new database or table), ALTER (change a table's structure), DROP (remove a table or database).

DML (Data Manipulation Language) — commands that work with the data inside the tables.

• Example commands: INSERT (add a new row), UPDATE (change existing data), DELETE (remove rows). (SELECT, used to read data, is studied along with DML.) …

Do not put CREATE or DROP under DML, or INSERT/UPDATE under DDL. The memory hook is: DDL builds the containers (tables …