Oracle Certification Notes: Part XIII

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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