1. Oracle preliminary understanding

Oracle development tools 1. before using Oracle for SQLPlus, you must first open the Oracle service. Find and open SQLPlus in the Start Menu. Open SQLPlus and enter the user name and password (scotttiger. PLSQLDeveloper click new-CommandWindow in the upper left corner to edit the SQL

Oracle development tools 1. before using Oracle for SQL Plus, you must first enable the Oracle service. In the Start Menu, find SQL Plus and enable it. enable SQL Plus and enter the username and password (scott/tiger ),: 2. PLSQL Developer click new-Command Window in the upper left corner to edit the SQL

Oracle development tools

1. SQL Plus
Before using Oracle, you must first open the Oracle service ,:

Find SQL Plus in the Start menu and open it ,:

Open SQL Plus and enter the username and password (scott/tiger ),:

2. PLSQL Developer

Click new-> Command Window in the upper left corner. The edit SQL Command interface is displayed ,:

Prepare database tables

1. Import the del_data. SQL database file on disk D ,:
   
2. Import the hr_cre. SQL database file on disk D ,:
   
3. Finally, import the hr_popul. SQL database file under drive D ,:
   
4. Relationship between tables ,:
   

SQL statements are categorized into the following types:

DML: Data Manipulation Language Data operation Language DDL: Data Definition Language DCL: Data Control Language

DML

DML is used to query and modify data records, including the following SQL statements:
-INSERT: add data to the database
-UPDATE: modify data in the database
-DELETE: deletes data from a database.
-SELECT: SELECT (query) data

DDL

DDL is used to define the structure of a database, such as creating, modifying, or deleting database objects. It includes the following SQL statements:
-Create table: CREATE a database TABLE
-Alter table: ALTER the TABLE structure, add, delete, and modify the column length.
-Drop table: delete a TABLE
-Create index: CREATE an INDEX on a table
-Drop index: delete an INDEX

DCL

DCL is used to control database access, including the following SQL statements:
-GRANT: GRANT access permissions.
-REVOKE: revoking Access Permissions
-COMMIT: COMMIT Transaction Processing
-ROLLBACK: Transaction ROLLBACK
-SAVEPOINT: Set the save point
-LOCK: LOCK specific parts of the database