This is a continuation of my notes as I study for the Oracle Certified Associate crediential:
Data Manipulation Language (DML)
5 DML commands: SELECT, INSERT, UPDATE, DELETE, MERGE
May INSERT into 1 row using VALUES; May INSERT into multiple rows using SELECT
May INSERT into multiple tables at a time. As an example: INSERT ALL WHEN column1=1 INTO table1(column1) VALUES (retrieved.column1) WHEN column2=2 INTO table2(column1) VALUES (retrieved.column2) SELECT column1, column2 FROM table3;
TRUNCATE is technically considered a command of the Data Definition Language (DDL)
MERGE can be thought of as a way to perform an INSERT, UPDATE, or DELETE depending on the data circumstance. Instead of coding for all 3 scenarios, a MERGE does it all at once.
CONTROL Transactions
COMMIT, ROLLBACK, SAVEPOINT are control transactions
Relational database standards for transactions – ACID: atomicity, consistency, isolation, durability
Example: SAVEPOINT savepoint
Example: >ROLLBACK [TO SAVEPOINT savepoint]
Terminating transaction statements include COMMIT, ROLLBACK, and TRUNCATE. SAVEPOINT and ROLLBACK TO SAVEPOINT does not terminate a transaction.
Database Objects
An object (e.g., table, stored procedure) is owned by a database user; a set of objects owned by a database user is referred to as its schema.
Object names can be no more than 30 characters consisting of letters, numbers, underscore (_), dollar sign ($) and hash symbol (#)
Objects are defined by their namespace and schema_owner.object_name
Namespace is a group of object types. Stored Procedures, Tables, Views, Synonyms, and Sequences are considered to be in a namespace. Indexes are stored in a separate namespace.
The amount of limited space assigned to a table is known as an extent.
Posted via Woodland Blog (http://dramse01.blogspot.com)
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