yefeng_laixi 发表于 2013-1-29 22:05:25

Oracle 语言分类(DDL,DML,DCL,TCL)

Oracle的语言分四类,它们是(数据定义语言DDL)、(数据操纵语言DML)、(数据控制语言DCL) 和 (事务控制语言TCL)
DDL  Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:
  CREATE - to create objects in the database
  ALTER - alters the structure of the database
  DROP - delete objects from the database
  TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
  COMMENT - add comments to the data dictionary
  RENAME - rename an object
DML
  Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:
  SELECT - retrieve data from the a database
  INSERT - insert data into a table
  UPDATE - updates existing data within a table
  DELETE - deletes all records from a table, the space for the records remain
  MERGE - UPSERT operation (insert or update)
  CALL - call a PL/SQL or Java subprogram
  EXPLAIN PLAN - explain access path to data
  LOCK TABLE - control concurrency
DCL
  Data Control Language (DCL) statements. Some examples:
  GRANT - gives user's access privileges to database
  REVOKE - withdraw access privileges given with the GRANT command
TCL
  Transaction Control (TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.
  COMMIT - save work done
  SAVEPOINT - identify a point in a transaction to which you can later roll back
  ROLLBACK - restore database to original since the last COMMIT
  SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use
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