Oracle's simple to understand

1. a cognitive
        awareness of what is oracle?
            oracle: the first commercial use of a relational database
            in real terms: relational database
        to understand the history of oracle database
    2. The two concepts of
        database: Data storage warehouse
        relational database: There may be some relationship between objects stored in the database, not the fully independent. Mainly reflected in the main after learning of a foreign key.
    3. three terms
        sql: Structured query language operating oracle database
        sqlplus: oracle sql can be entered with the software, and the results show that the terminal sql execution
        pl / sql : programmed sql statement, sql statement is added on the basis of a certain logic operations, as if for ..., making a sql block, complete certain functions
    4. the four kinds of objects
        table: tables, rows and columns composition, also known as field column, each row of content is a complete data table.
        view: partial view, a table or multiple tables or the complete mapping table like the mirror, the mirror image is a virtual view of the inside
        than two kinds of common table and view objects removed, oracle database also supports the following four target
        sequence: sequence
        index: the index to improve the efficiency of data access
        operations synonymous, convenient object: synonym
        program unit: program units, pl / sql operation target
    5. The five classes of
        five classification of sql:
        the Data Retrieval: Data Query
                                the DDL: Data Definition Language (table level operations Language): The contents of the operation table (object)
        Create drop ALTER truncate rename need to submit

                                DQL: data query language
        the SELECT

        DML: data manipulation language (row-level manipulation language): operation is a table among a one of the data
        INSERT Update the Delete

        DTL: transaction control language
        transaction control: transaction control    
        the commit ROLLBACK that the savepoint

        DCL: data control language
        Grant REVOKE
    
        
    the delete, TRUNCATE difference:
        the delete: delete one or multiple records in the table, the operation will need to submit the transaction
        truncate: empty tables, this operation does not need to commit the transaction



oracle database environment to prepare:
    1. install oracle database
        1.1 in accordance with the best default to the C drive
        and 1.2-step installation process allows to enter a password, it is recommended to use oracle as the password easy to remember
        after 1.3 installation is complete, open the system service to see if the service has started normally, with reference to the specific circumstances of the document: oracle system services .txt
        1.4 opens cmd, enter sqlplus, then press enter to see if you can execute the command
        1.5 If you can not perform, you need to make installation directory inside the BIN configured into the system environment variable in the path, and then re-open a cmd window to

    2. Log oracle own management system, a new one of their own account.
        reference document: oracle system services .txt

    3. Once the user is created, use the command sqlplus log on to the oracle database and then later put to use to the table and import its data into the database
        reference documentation: importing data .txt
    
    4. understand the import of the three tables and the relationship
        s_emp employees table
        s_dept department table
        s_region region table

    Login or operation of the database after 5, you can use this newly created user the