DDL 与 DML

• 数据定义语言(DDL): Data Definition Language

1. CREATE - to create objects in the database
 2. ALTER - alters the structure of the database
 3. DROP - delete objects from the database
 4. TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
 5. COMMENT - add comments to the data dictionary
 6. RENAME - rename an object

• 数据操纵语言(DML): Data Manipulation Language

1. SELECT - retrieve data from the a database
 2. INSERT - insert data into a table UPDATE - updates existing data within a table
 3. DELETE - deletes all records from a table, the space for the records remain
 4. MERGE - UPSERT operation (insert or update)
 5. CALL - call a PL/SQL or Java subprogram
 6. EXPLAIN PLAN - explain access path to data
 7. LOCK TABLE - control concurrency