oracle 12 tutorial

Oracle 12c is one of the most commonly used enterprise-level database systems today. With the rapid increase in data volume and further complexity of business, many enterprises have begun to use Oracle 12c to manage and store data. However, Oracle 12c has many complex functions, and many new functions have appeared with the increase of versions. For beginners, this system can be a little tricky. Therefore, in this tutorial, you will be introduced to some important concepts of Oracle 12c and how to use this database system.

1. Installing Oracle 12c

Before using Oracle 12c, you need to install it. First, you need to download the installation files for Oracle 12c. Once completed, run the installer. Make sure you have the correct version of Java installed on your computer and have the appropriate permissions to install the software. The installation steps require you to complete the following steps:

• Select which components you need to install
• Specify the Oracle automatic confirmation file (by default, this file will be generated using the installer)
• Specify the Oracle software management method (there are two options: use ENTRPRSDB or use SYSDBA as primary access)
• Specify the Oracle Inventory directory (by default, it will be /opt/oracle/oraInventory)
• Specify the Oracle home directory (by default, it will be /opt/oracle/product/12c/dbhome_1)

During installation, you will need to enter the Oracle superuser account password, and the password for the administrator account of the Oracle 12c database. Once completed, you can boot Oracle 12c and start using it.

2. Connecting to Oracle 12c database

In order to connect to Oracle 12c, you need to start the Oracle 12c service first. You can then connect to the Oracle 12c database using SQL PLUS. SQL PLUS is a command line tool used to enter commands and interact with the database.

At the command prompt, type:

$ sqlplus /nolog

This will open SQL *PLUS, then enter:

SQL> connect /as sysdba

This will connect you to the Oracle database. After entering the password, you can enter the main command line prompt, where you can enter any command.

3. Import and Export Files

Oracle 12c allows you to import and export data from other databases or text files. In order to import data from a file, you need to create a table for the data file. Here is some sample code to create a table:

CREATE TABLE my_table (
col1 NUMBER,
col2 VARCHAR2(10),
col3 DATE
);

After the table is created, you can use the following command to import data:

sqlldr userid=username/password@dbname control=example.ctl

• or use the following command to export data:

sqlplus username/password@dbname
oracle home/bin/exp file=example.dmp tables=my_table

The function of these commands is to import or export data to a file .

4. Creating tables and defining fields

In Oracle, tables are the basic unit for storing data. Therefore, it is very important to design the correct tables for the tables in the database. Before creating a table, you need to define the fields in the table. Here is some sample code on how fields are defined and how they are used when creating a table:

Column Name Data Type (Size) Data Constraints
id NUMBER(10) NOT NULL
name VARCHAR2(30 ) NOT NULL
age NUMBER(3) DEFAULT 0
gender CHAR(1) NOT NULL
address VARCHAR2(100)

Using the above code, you can define some common field attributes, Such as ID, name, age, gender and address. Define field properties as field name, data type, size and constraint information.

Here is some sample code on how to create a table:

CREATE TABLE my_table (
id NUMBER(10) NOT NULL,
name VARCHAR2(30) NOT NULL,
age NUMBER(3) DEFAULT 0,
gender CHAR(1) NOT NULL,
address VARCHAR2(100),
PRIMARY KEY (id)
);

These codes What it does is create a table named my_table and add the defined fields and their properties.

5. Insert and query data

After defining the table and its fields, you can insert data into it. Here is some sample code on how to insert data and query the data:

INSERT INTO my_table (id, name, age, gender, address)
VALUES (1001, 'Tom', 25, 'M', 'Shanghai');

SELECT * FROM my_table;

Using the above command, you can insert data into the my_table table and use the "SELECT" command to query all data in the table.

6. Create an index

Index is a technique used to speed up database queries. It helps Oracle find matching records faster. In Oracle, a basic unique index can be created using the following command:

CREATE UNIQUE INDEX my_index ON my_table(id);

This command creates an index named my_index, which Based on the id field and unique. When the query speed is slow, using the index can speed up the corresponding query.

7. Using Oracle Sequences

Sequences are very common in Oracle databases. They are used to generate values ​​for auto-increment or auto-fill fields. Sequences have many uses, such as creating primary keys or other unique ID values. Here is some sample code on how to create a sequence in Oracle:

CREATE SEQUENCE my_sequence
START WITH 1
INCREMENT BY 1
NOCACHE
NOCYCLE;

The function of these codes is to create a sequence named my_sequence. The sequence starts at 1 and ends with an increment of 1 each time. The sequence is not cached and does not loop.

8. Create a stored procedure

A stored procedure is a reusable block of code that is executed in the database. They are used to perform complex queries or perform more complex data validation. Here is some sample code on how to create a stored procedure:

CREATE OR REPLACE PROCEDURE my_proc
IS
BEGIN
SELECT * FROM my_table WHERE id = 100;
END;

The function of these codes is to create a stored procedure named my_proc, which queries the data row with id 100 in the my_table table.

Summary

In this tutorial, you learned some basic concepts about Oracle 12c and how to install, connect, import and export data, create tables, define fields, insert and query data, Create indexes, use sequences, create stored procedures, and more. This content should be enough to get you started storing and managing your data in Oracle 12c. I hope this tutorial can help you understand Oracle 12c and be helpful in your work.

The above is the detailed content of oracle 12 tutorial. For more information, please follow other related articles on the PHP Chinese website!