Oracle Developer Tutorial for Beginners: Take Your First Step

Data is critical in today’s corporate environment. The need for Oracle developers who can create and manage the required database infrastructure and apps is growing as more and more organizations rely on data-driven insights to inform their strategic decisions. Begin your first step with this Oracle developer tutorial for beginners. Explore our Oracle Course Syllabus to get started on your DBA journey.

Oracle Basics for Beginners

While there are many other aspects of Oracle development, the main focus is on working with and creating applications that make use of Oracle databases. Understanding the foundations of SQL (Structured Query Language) is usually the first step for beginners. From there, you can use Oracle’s development tools and possibly PL/SQL (Procedural Language/SQL).

SQL Fundamentals

Relational database management systems (RDBMS), such as Oracle, use SQL as their standard language for data management and manipulation. Data and database structures can be created, read, updated, and deleted with SQL. 

Basic SQL Commands

SELECT: It pulls information out of one or more tables. The SQL command that is used the most is this one.

Syntax:

SELECT column1, column2, …

FROM table_name;

or

SELECT * FROM Employees;

FROM: It indicates the table or tables you wish to retrieve data from. The SELECT command is always used in combination with it.

Syntax:

FROM table_name;

WHERE: It applies a provided condition to filter the rows that the SELECT operation returns.

Syntax:

SELECT column1, column2, …

FROM table_name

WHERE condition;

Common Comparison Operators in WHERE Clause: 

=, >, <, >=, <=, <> (not equal), != (not equal), BETWEEN, LIKE, IN, IS NULL, IS NOT NULL.

INSERT INTO: It adds additional data rows to a table.

Syntax:

INSERT INTO table_name (column1, column2, …)

VALUES (value1, value2, …);

Inserting into All Columns: You can skip the column list if you’re entering data for every column in the table:

INSERT INTO Employees

VALUES (102, ‘Bob’, ‘Johnson’);

UPDATE: It alters the data that is already in a table. The WHERE clause must be used with UPDATE in order to prevent inadvertently updating every record.

UPDATE table_name

SET column1 = value1, column2 = value2, …

WHERE condition;

DELETE FROM: It eliminates a table’s rows. Always indicate specific rows to remove using a WHERE clause, just like with UPDATE.

DELETE FROM table_name

WHERE condition;

Deleting All Rows: You can skip the WHERE clause in order to remove every row from a table while maintaining the table’s structure:

DELETE FROM Employees;

CREATE TABLE: It creates a new database table. The column names and data types must be specified.

CREATE TABLE table_name (

    column1 datatype constraints,

    column2 datatype constraints,

    …

);

ALTER TABLE: It alters an existing table’s structure. Columns can be added, changed, or removed, and constraints can be added or removed.

ALTER TABLE table_name

ADD column_name datatype constraints;

DROP TABLE: This removes a table in its entirety, together with all of its information and organization. Be very careful when using this command!

DROP TABLE table_name;

Kickstart your journey with our Oracle Online Course Program.

Data Types in Oracle

The extensive collection of built-in data types that Oracle provides can be broadly divided into the following categories:

Character Data Types: 

These are used to store alphanumeric data (letters, numbers, symbols).

• VARCHAR2: Variable-length character string (size [BYTE | CHAR]). The maximum size is specified in characters or bytes. In general, VARCHAR2 is better than VARCHAR.
• NVARCHAR2(size): You can store characters from different languages using the variable-length Unicode character string NVARCHAR2(size). Characters are used to specify the size.
• CHAR(size [BYTE | CHAR]): A string of characters with a fixed length. Oracle adds spaces to the saved string if it is less than the specified length.
• NCHAR(size): Unicode character string of fixed length.
• Character large objects, or CLOBs, can hold up to 4 terabytes of single- or multi-byte character data (or database block size depending).
• NCLOB: Large blocks of Unicode character data are stored in NCLOBs (National Character Large Objects).
• LONG: Up to two gigabytes of variable-length character string. Generally speaking, CLOB is advised for new applications primarily for backward compatibility. 

Numeric Data Types: 

These are used to store numbers.

• NUMBER[(precision [, scale])]: Holds fixed or floating-point integers with a given scale (number of digits to the right of the decimal point) and precision (total number of digits).
• INTEGER, INT, SMALLINT: NUMBER subtypes for storing whole numbers are INTEGER, INT, and SMALLINT.
• NUMERIC[(precision [, scale])]: ANSI-specific fixed-point numeric types are DECIMAL[(precision [, scale])], DEC[(precision [, scale])], and NUMERIC[(precision [, scale])].
• FLOAT[(precision)]: A floating-point number with a given binary precision is denoted. It is a NUMBER subclass.
• REAL: A floating-point number with around 18 decimal places and a binary precision of 63. It is a FLOAT subtype.
• DOUBLE PRECISION: The floating-point number has a binary precision of 126, which is equivalent to about 38 decimal places. It is a FLOAT subtype.
• BINARY_FLOAT: IEEE 754 formatted 32-bit single-precision floating-point number.
• BINARY_DOUBLE: 64-bit double-precision floating-point number in IEEE 754 format.

Date and Time Data Types: 

Date and time data are stored using these types.

• DATE: Keeps track of the day, time, hour, minute, second, year, and month.
• TIMESTAMP[(fractional_seconds_precision)]: Adds fractional seconds to the DATE type.
• TIMESTAMP WITH TIME ZONE: Provides the date, time, and time zone information.
• TIMESTAMP WITH LOCAL TIME ZONE: The timestamp is displayed in the user’s session time zone, while it is stored in the database time zone.
• INTERVAL YEAR [(precision_year)] TO MONTH: Holds a time span in months and years.
• DAY INTERVAL[(day_precision)] TO SECOND[(fractional_seconds_precision)]: Holds a time interval in minutes, seconds, days, and hours. 

Large Object (LOB) Data Types: 

These are used to store large, unstructured data.

• BLOB: Large binary data, such as pictures, audio, and video, can be stored in BLOB (Binary Large Object).
• CLOB: Large character data blocks are stored using CLOBs (Character Large Objects), as was previously explained.
• NCLOB: Large blocks of Unicode character data are stored via NCLOBs (National Character Large Objects), as was previously explained.
• BFILE (Binary File): Holds a pointer to an operating system binary file that is not in the database.

ROWID Data Types:

The physical address of a table row is represented by ROWID data types.

• ROWID: A row’s physical address in a standard table.
• UROWID: For tables that are index-organized, UROWID (Universal ROWID) is a logical address that can also hold foreign ROWIDs. 

Other Data Types:

• RAW(size): Binary data with variable length up to 2000 bytes.
• LONG RAW: Up to two terabytes of variable-length binary data. Backward compatibility is the main reason BLOB is usually advised.
• BOOLEAN (PL/SQL only): TRUE, FALSE, or NULL are the only logical values that can be stored in PL/SQL.
• XMLType: Holds XML information.
• Spatial Data Types (SDO_GEOMETRY, etc.): Used to manage and store spatial data.
• Media Data Types (ORDImage, ORDVideo, etc.): ORDImage, ORDVideo, and other media data types are used for handling and storing multimedia data.

Review your skills with our Oracle Interview Questions and Answers.

Operators in Oracle

In Oracle, operators are reserved words or symbols that manipulate one or more values, called operands. In your SQL statements and PL/SQL code, they let you combine conditions, compare values, and work with data.

Arithmetic Operators: 

These perform mathematical calculations.   

Comparison Operators:

It returns a Boolean value (TRUE, FALSE, or UNKNOWN) after comparing two expressions. They are frequently utilized in conditional statements and WHERE clauses.

Logical Operators:

They are used in WHERE clauses and other logical expressions to combine or change the conditions.

SET Operators:

The output of two or more SELECT statements is combined by set operators.

String Operators: 

These operators manipulate character strings.

Other Operators:

• BETWEEN… AND…: (Previously discussed under Comparison, but it’s important to note its particular application to ranges).
• IN (…): (Previously discussed under Comparison, for comparing to a list).
• LIKE: (Previously discussed under Comparison, for pattern matching, use % for any character sequence and _ for a single character).
• ALL: Evaluates a value against every value in a subquery or list.
• ANY or SOME: A value can be compared to any value in a list or subquery using it.
• EXISTS: Verifies whether rows are present in a subquery. 

Clauses in Oracle

Important SQL clauses include JOIN (for joining data from various tables), HAVING (for filtering grouped data), GROUP BY (for aggregating data), and ORDER BY (for sorting).

JOIN Clauses in Oracle:

Using a linked column between two or more tables, combine their rows.

• INNER JOIN: Only when there is a match in both tables does an INNER JOIN (or simply JOIN) return rows.
• LEFT JOIN: All rows from the left table and the corresponding rows from the right table are returned by an LEFT JOIN (also known as an LEFT OUTER JOIN). It returns NULL for the columns in the correct table if there isn’t a match.
• RIGHT JOIN: All rows from the right table and the corresponding rows from the left table are returned by a right join, also known as a right outer join. It returns NULL for the columns in the left table if there isn’t a match.
• FULL OUTER JOIN: When there is a match in either the left or right table, the FULL OUTER JOIN (also known as FULL JOIN) returns every row. It returns NULL for the table’s columns if there isn’t a match in any of the tables.
• CROSS JOIN: The Cartesian product of all rows from all linked tables is returned by a cross join, which combines all of the rows from the first and second tables.

Syntax:

SELECT e.first_name, d.department_name

FROM Employees e

INNER JOIN Departments d ON e.department_id = d.department_id;

HAVING Clauses in Oracle:

It filters a GROUP BY clause’s output according to predetermined criteria. Though it works on the aggregated rows instead of the individual rows, it is comparable to WHERE.

Syntax:

HAVING group_condition

GROUP BY Clauses in Oracle:

It creates summary rows by combining rows with the same values in one or more designated columns. frequently combined with aggregate functions (such as AVG, MIN, MAX, SUM, COUNT, and SUM).

Syntax:

GROUP BY column1, column2, …

ORDER BY Clauses in Oracle:

It uses one or more columns to sort the rows in the result set.

Syntax:

ORDER BY column1 [ASC | DESC], column2 [ASC | DESC], …

If you are around OMR, you can enroll in our Oracle Training in OMR.

Functions in Oracle

Functions enable you to carry out particular operations on data values and are crucial tools in Oracle SQL and PL/SQL. You can make your own custom functions in addition to using Oracle’s extensive library of built-in functions.

String Functions:

Used to perform character operations. Some of the popular string functions are:

• UPPER(string): The function UPPER(string) changes a string to uppercase; for example, UPPER(‘hello’) yields ‘HELLO’.
• LOWER(string): A string can be converted to lowercase using the LOWER(string) function; for example, LOWER(‘WORLD’) yields ‘world’.
• INITCAP(string): Returns ‘The Quick Brown Fox’ after converting the initial letter of each word to uppercase and the other letters to lowercase.
• CONCAT(string1, string2): The || operator is similar to CONCAT(string1, string2), which concatenates two strings.

Numeric Functions:

Used to perform mathematical operations. Some of them are:

• ROUND(number [, decimals]): A number can be rounded to a predetermined number of decimal places using the ROUND(number [, decimals]) function.
• TRUNC(number [, decimals]): Removes digits without rounding and truncating a number to a predetermined number of decimal places.
• MOD(dividend, divisor): The remainder of a division is returned by MOD(dividend, divisor).
• FLOOR(number): The greatest integer that is less than or equal to a number is returned by the FLOOR(number) function.

Date and Time Functions: 

Change the values of the date and time. Some of them are:

• SYSDATE: Provides the operating system’s current date and time on the database server.
• CURRENT_DATE: The current date in the session time zone is returned by it.
• CURRENT_TIMESTAMP[(precision)]: The current timestamp in the session time zone, with optional fractional seconds precision, is returned by it.
• SYSTIMESTAMP[(precision)]: Provides the operating system timestamp of the database server as of right now, with the option to include fractional seconds.

Conversion Functions: 

They are used to change values between different types of data.

• TO_CHAR(number [, format_mask]): This function uses a given format mask to convert a number to a character string.
• TO_NUMBER(string [, format_mask]): This function uses a given format mask to convert a character string to a NUMBER data type.
• CAST(expression AS datatype): An expression can be converted to a specific data type using the CAST(expression AS datatype) function.

Aggregate Functions (Group Functions): 

These functions return a single summary result for the group after operating on a collection of rows. The GROUP BY clause is frequently used with them.

COUNT([DISTINCT] column | *): The number of rows in a group (or, if a column is supplied, the number of non-null values in a column) is returned by it. All rows are counted by COUNT(*). Only the distinct non-null values are counted by COUNT(DISTINCT column).

SUM(column): Provides the total of the values in a column that contains numbers.

AVG(column): The average of the numbers in a numeric column is returned by this function.

MIN(column): Gives back a column’s lowest value.

MAX(column): The maximum value in a column is returned by the MAX(column) function.

STDDEV(column): The standard deviation of the values in a numeric column is returned by it.

VARIANCE(column): The variance of the values in a numeric column is returned by it.

Learn DBA from scratch with our database administrator training in Chennai.

Setting up your Oracle Development Environment

Oracle Database

Access to an Oracle database is required. You have a few choices for educational purposes:

• Oracle Database Free: You can download and install this fully functional version on your home computer for free.
• Oracle Autonomous Database Free Tier: The Autonomous Database is one of Oracle’s “Always Free” cloud services that you can access via a web browser.
• Live SQL: Oracle offers Live SQL, a free browser-based application that lets you create and run SQL queries without the need for any installation. 

SQL Developer

The free integrated development environment (IDE) Oracle SQL Developer makes managing and developing Oracle databases easier. For authoring and running SQL and PL/SQL, viewing database objects, and carrying out administrative duties, it offers an intuitive user interface. It is available for download on the Oracle website. 

SQLcl (SQL Developer Command Line): 

A contemporary and free command-line tool for working with Oracle databases is called SQLcl (SQL Developer Command Line). It has features like command history and auto-completion and is lightweight. 

Recommended: Oracle SQL Training in Chennai.

Introduction to PL/SQL

Oracle’s procedural version of SQL is called PL/SQL. It lets you develop code blocks with variables, loops, conditions, and exception handling by fusing SQL with procedural programming techniques. This lets you create more complex stored procedures, triggers, functions, and database applications.

Basic PL/SQL Concepts:

• Blocks: PL/SQL code is arranged in either named or anonymous blocks.
• Variables and Data Types: Declare and utilize variables in PL/SQL blocks to store data.
• Control Structures: Some of the loop constructs (FOR, WHILE, LOOP), CASE, and IF-THEN-ELSE.
• Cursors: We can use cursors to retrieve and handle several rows of data from a query.
• Exceptions: We can deal with errors that arise when PL/SQL is being executed.
• Stored Procedures and Functions: We can create reusable PL/SQL code units that may be saved in a database and used by apps or other database code by learning about stored procedures and functions.
• Triggers: It is used to design database triggers, which are PL/SQL blocks that run automatically when certain database actions (such adding, editing, or removing data) occur. 

Suggested: Oracle PL/SQL Training in Chennai.

Oracle Developer Tools

A wide range of tools are available to you as an Oracle Developer to help with different phases of development, from designing and querying databases to creating and deploying applications. 

Oracle SQL Developer: 

An open-source integrated development environment (IDE) that makes Oracle database creation and administration easier, both on-site and in the cloud. This is a primary tool for Oracle developers. It offers features for:

• Writing and executing SQL and PL/SQL.
• Browsing and managing database objects (tables, views, procedures, etc.).
• Debugging PL/SQL code.
• Data modeling.
• Migrating databases.
• Generating reports.

Oracle Developer Tools for Visual Studio (ODT):

.NET developers may connect to and work with Oracle databases using this free add-on for Microsoft Visual Studio. Some of its key features are:

• Server Explorer Integration
• Oracle Autonomous Database Integration
• PL/SQL Editor and Debugger
• Schema Compare Tools
• Entity Framework Designers and Wizards
• Automatic .NET Code Generation
• Application Tuning Tools
• SQL Script Lifecycle with Source Control

Oracle JDeveloper:

The primary goal of this integrated development environment (IDE) is to create Java-based applications, particularly those that communicate with Oracle databases. Some of its key features are:

• All-inclusive Java development tools.
• Support for creating enterprise apps using the Oracle Application Development Framework (ADF).
• Visual editors for data modeling and user interface design.
• Integration with middleware and database technologies from Oracle.

Oracle APEX (Application Express):

a platform for low-code development that lets you create safe, scalable web and mobile apps using Oracle databases. Some of its features are:

• Environment for development that is browser-based.
• Drag-and-drop components in declarative development.
• Inherent security measures.
• Simple deployment both on-premises and to Oracle Cloud.

Oracle REST Data Services (ORDS): 

A tool that facilitates the creation of contemporary REST APIs for PL/SQL processes and data from Oracle databases. Some of its features are:

• Uses database objects to generate RESTful web services.
• JSON and other formats are supported.
• Offers monitoring and security features.

Oracle Cloud Infrastructure (OCI) Developer Tools:

A selection of services and tools on Oracle’s cloud platform that assist developers in creating, deploying, and maintaining cloud applications. Its key features are:

• OCI Command Line Interface (CLI)
• OCI SDKs
• OCI DevOps Services
• Container Technologies (Docker, Kubernetes)
• AI and Machine Learning Services

Oracle Data Modeler:

An independent, free graphical data modeling tool. Additionally, SQL Developer can be integrated with it. Its features are:

• Construct data type, multi-dimensional, physical, relational, and logical models.
• Database schemas are both forward and backward engineered.
• Integrates source code control to facilitate collaborative development.

Oracle Developer Studio:

Compilers and debugging tools are provided by this commercial software development product for the Linux and Solaris operating systems.

Your unique requirements, the kind of application you are creating, your desired development environment, and the Oracle technologies you are using will all influence which Oracle developer tool is best for you.

Explore all our IT training courses here.

Conclusion

To support cutting-edge development methodologies and the dynamic Oracle ecosystem, which includes its cloud solutions, Oracle keeps investing in and improving its developer tools. We hope you have gained fundamental understanding with this Oracle Developer Tutorial. Hone your skills with our Oracle training in Chennai.