DDL AND DML COMMANDS

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.

DDL is a set of SQL commands used to create, modify, and delete database structures but not data. These commands are normally not used by a general user, who should be accessing the database via an application.

List of DDL Commands:

Here are all the main DDL (Data Definition Language) commands along with their syntax:

Command	Description	Syntax
CREATE	Create database or its objects (table, index, function, views, store procedure, and triggers)	`CREATE` `TABLE table_name (column1 data_type, column2 data_type, ...);`
DROP	Delete objects from the database	`DROP` `TABLE table_name;`
ALTER	Alter the structure of the database	`ALTER` `TABLE table_name ADD COLUMN column_name data_type;`
TRUNCATE	Remove all records from a table, including all spaces allocated for the records are removed	`TRUNCATE` `TABLE table_name;`
COMMENT	Add comments to the data dictionary	`COMMENT` `'comment_text' ON TABLE table_name;`
RENAME	Rename an object existing in the database	`RENAME` `TABLE old_table_name TO new_table_name;`

DML (Data Manipulation Language)

The SQL commands that deal with the manipulation of data present in the database belong to DML or Data Manipulation Language and this includes most of the SQL statements.

It is the component of the SQL statement that controls access to data and to the database. Basically, DCL statements are grouped with DML statements.

List of DML commands

Here are all the main DML (Data Manipulation Language) commands along with their syntax:

Command	Description	Syntax
INSERT	Insert data into a table	`INSERT` `INTO table_name (column1, column2, ...) VALUES (value1, value2, ...);`
UPDATE	Update existing data within a table	`UPDATE` `table_name SET column1 = value1, column2 = value2 WHERE condition;`
DELETE	Delete records from a database table	`DELETE` `FROM table_name WHERE condition;`
LOCK	Table control concurrency	`LOCK` `TABLE table_name IN lock_mode;`
CALL	Call a PL/SQL or JAVA subprogram	`CALL` `procedure_name(arguments);`
EXPLAIN PLAN	Describe the access path to data	`EXPLAIN` `PLAN` `FOR SELECT * FROM table_name;`