PostgreSQL - ADD COLUMN Last Updated : 19 Nov, 2024 Comments Improve Suggest changes Like Article Like Report In PostgreSQL, the ADD COLUMN statement is a powerful command used to modify an existing database table by adding one or more new columns. This feature is important for adapting table structures to meet evolving data requirements, and it plays a key role in database management and optimization.In this article, we will explain how to effectively use the ADD COLUMN statement in PostgreSQL, with practical examples, detailed explanations, and tips for optimizing its use. We’ll also discuss common scenarios and best practices to help us get the most out of this command.What is PostgreSQL ADD COLUMN?The ADD COLUMN statement is part of the ALTER TABLE command in PostgreSQL, allowing us to add new columns to an existing table. Once added, the new column will be appended to the end of the table, and we can specify attributes such as the column's data type, default value, and constraints. However, it’s important to note that PostgreSQL doesn’t support directly setting the position of the new column within the table.SyntaxALTER TABLE table_nameADD COLUMN new_column_name data_type;Parameterstable_name: The name of the table to which the column is being added.new_column_name: The name of the new column.data_type: The data type for the new column (e.g., VARCHAR, INTEGER, DATE, etc.).constraint: Optional. Constraints like NOT NULL, UNIQUE, or DEFAULT can be applied to the new column.Key PointsThe ADD COLUMN statement always appends the new column at the end of the table.PostgreSQL does not support specifying the position of the new column within the table (i.e., columns can’t be inserted at a specific position).We can add multiple columns in a single ALTER TABLE statement by separating them with commas.Examples of PostgreSQL ADD COLUMNLet us take a look at ADD COLUMN Statement in PostgreSQL to better understand the concept and explore how it can be applied to real-world database scenarios effectivelyExample 1: Adding a Column to the Village TableFirst, create a table named 'village' which contains two columns 'village_id' and 'village_name' columns: Step 1: Create the tableCREATE TABLE village( village_id SERIAL PRIMARY KEY, village_name VARCHAR NOT NULL);Step 2: Add a new column to the tableTo add a district column of type VARCHAR, we use the following ALTER TABLE statement:ALTER TABLE villageADD COLUMN district VARCHAR; Step 3: Verify the changesNow we can verify if the column has been added using the below statement: SELECT * FROM village;OutputExplanation: The district column has been successfully added to the village table.Since no DEFAULT value was specified, the value for the new column is NULL for all existing rows.Example 2: Adding a Column to the Cars TableFirst, create a table named 'cars' with 'car_id' and 'car_name' columns:Step 1: Create the tableCREATE TABLE cars( car_id SERIAL PRIMARY KEY, car_name VARCHAR NOT NULL);Step 2: Add a new column with a default valueNow we add a model column with a default value of 'Unknown' to the table as below ALTER TABLE carsADD COLUMN model VARCHAR;Step 3: Verify the changes Now we can verify if the column has been added using the below statement: SELECT * FROM cars;OutputExplanation: The model column has been added to the cars table.All existing rows have been assigned the default value of 'Unknown' for the new column.Important Points About ALTER TABLE ADD COLUMN StatementWhen a new column is added to a table, PostgreSQL appends it at the end. PostgreSQL does not allow setting the position of the new column within the table.We can specify default values for the new column. If not specified, the default is 'NULL'.Adding a column can lock the table, preventing other operations. This lock is typically brief but can be longer for large tables or complex operations.Columns can be added based on expressions or existing columns. However, the initial value for all rows will be the same unless updated afterward.ConclusionThe PostgreSQL ADD COLUMN statement is a powerful and flexible tool for modifying the structure of our database tables. By using this command, we can easily add new columns to adapt evolving data needs. While PostgreSQL appends new columns to the end of the table, we can manage column attributes like default values, unique constraints, and data types to meet our specific requirements. Comment More infoAdvertise with us Next Article PostgreSQL - DROP COLUMN R RajuKumar19 Follow Improve Article Tags : PostgreSQL Databases postgreSQL-managing-table Similar Reads BasicsPostgreSQL TutorialIn this PostgreSQL tutorial you’ll learn the basic data types(Boolean, char, text, time, int etc.), Querying and Filtering techniques like select, where, in, order by, etc. managing and modifying the tables in PostgreSQL. We’ll cover all the basic to advance concepts of PostgreSQL in this tutorial.8 min readWhat is PostgreSQL - IntroductionThis is an introductory article for the PostgreSQL database management system. In this we will look into the features of PostgreSQL and why it stands out among other relational database management systems. Brief History of PostgreSQL: PostgreSQL also known as Postgres, was developed by Michael Stone2 min readInstall PostgreSQL on WindowsInstalling PostgreSQL on your Windows 10 machine is straightforward with the PostgreSQL installer. In this article, we'll walk you through installing PostgreSQL version 11.3, ensuring a smooth setup process.Steps to Install PostgreSQL on WindowsThere are three crucial steps for the installation of P2 min readInstall PostgreSQL on MacInstalling PostgreSQL on Mac OS can enhance our development environment, providing a robust relational database management system. In this article, we will focus on installing PostgreSQL version 11.3 using the installer provided by EnterpriseDB. This step-by-step guide will ensure a smooth installat3 min readDatabase OperationsPostgreSQL - Create DatabaseCreating a database in PostgreSQL is an important task for developers and database administrators to manage data effectively. PostgreSQL provides multiple ways to create a database, catering to different user preferences, whether through the command-line interface or using a graphical interface like5 min readPostgreSQL - Loading a DatabaseIn this article we will look into the process of loading a PostgreSQL database into the PostgreSQL database server. Before moving forward we just need to make sure of two things: PostgreSQL database server is installed on your system. A sample database. For the purpose of this article, we will be us3 min readPostgreSQL ALTER DATABASEThe PostgreSQL ALTER DATABASE statement is a powerful tool used for modifying an existing database.  The features of a database, once created can be changed using the ALTER DATABASE statement. Let's explore the syntax of PostgreSQL ALTER DATABASE, the various actions that can be performed, and pract3 min readPostgreSQL - Rename DatabaseRenaming a PostgreSQL database is a simple yet essential task for developers and database administrators. Whether we're migrating data, restructuring our database, or just managing our server efficiently, the ability to rename a PostgreSQL database can streamline our workflow. In this article, we wi4 min readPostgreSQL - Show DatabasesIn PostgreSQL, viewing a list of all databases on a server requires specific commands, as it doesn’t support a direct SHOW DATABASES statement like MySQL. Instead, you can use the \l or \l+ commands in psql or query the pg_database view to display all databases. In this article, we will guide us thr3 min readData TypesPostgreSQL - Data TypesPostgreSQL is a powerful, open-source relational database management system that supports a wide variety of data types. These data types are essential for defining the nature of the data stored in a database column. which allows developers to define, store, and manipulate data in a way that aligns w5 min readPostgreSQL - Boolean Data TypePostgreSQL's Boolean data type supports three states: TRUE, FALSE, and NULL. It uses a single byte to store Boolean values and can be abbreviated as BOOL. In this article, we will explain the PostgreSQL BOOLEAN data type and its implementation in database table design, highlighting its usage through4 min readPostgreSQL - CHAR Data TypeThe CHAR data type in PostgreSQL is one of the essential character data types for storing fixed-length strings. Unlike VARCHAR, which stores variable-length data, CHAR is used when we need to store a fixed-length string.This article will explain the CHAR data type in PostgreSQL, its syntax, common u5 min readPostgreSQL - VARCHAR Data TypeIn the world of relational databases, PostgreSQL stands out with its robust support for various data types, including the flexible VARCHAR data type. This character data type allows us to store strings of variable length, making it an essential choice for many applications.In this article, we will e3 min readPostgreSQL - NUMERIC Data TypeIn PostgreSQL, the NUMERIC data type is designed for high-precision number storage by making it ideal for financial and scientific applications where accuracy is critical. It supports a large number of digits both before and after the decimal point, minimizing rounding errors. Understanding the nuan5 min readPostgreSQL - Date Data TypePostgreSQL offers powerful DATE data type and date functions to efficiently handle date and time information. PostgreSQL DATE data type allows for storing and manipulating calendar dates while its robust set of date functions enables users to perform operations like date arithmetic and formatting. I4 min readPostgreSQL - TIME Data TypeIn PostgreSQL, the TIME data type is essential for applications that require precise time tracking, such as scheduling systems and event logging. This data type allows for accurate time-based entries without storing date information. PostgreSQL’s TIME data type also supports fractional seconds for u4 min readPostgreSQL - JSON Data TypeJSON (JavaScript Object Notation) is a widely used format for storing data in the form of key-value pairs. Its popularity comes from being easy for humans to read and understand, making it ideal for communication between servers and clients. This readability and ease of use have made JSON a standard4 min readPostgreSQL - CREATE DOMAINPostgreSQL supports the creation of user-defined data types through the CREATE DOMAIN and CREATE TYPE statements. These capabilities allow for the customization and extension of data types to fit specific application needs, providing more flexibility and control over data integrity and consistency.3 min readQuerying TablesPostgreSQL - SELECTPostgreSQL SELECT statement is an command for retrieving data from tables within a PostgreSQL database. It enables users to specify which columns to fetch and apply filters using the WHERE clause for targeted results.In this article, We will learn about the PostgreSQL SELECT in detail by understandi3 min readPostgreSQL - ORDER BY clauseThe PostgreSQL ORDER BY clause is used to sort the result query set returned by the SELECT statement. As the query set returned by the SELECT statement has no specific order, one can use the ORDER BY clause in the SELECT statement to sort the results in the desired manner. Syntax: SELECT column_1, c2 min readPostgreSQL - WHERE clauseThe PostgreSQL WHERE clause is a critical component of SQL queries, allowing users to filter records based on specified conditions. In this tutorial, we'll explore how the WHERE clause works in PostgreSQL, its integration with the SELECT statement, and various examples. By using the WHERE clause, we6 min readPostgreSQL FETCH ClauseThe PostgreSQL FETCH clause is an essential feature for controlling and managing the number of rows returned in our SQL queries. It provides a standardized approach for limiting results, similar to the LIMIT clause but with more flexibility and compatibility across different database systems. This a4 min readPostgreSQL - IN operatorThe IN operator in PostgreSQL is a powerful and efficient tool used to filter records based on a predefined set of values. When used with the WHERE clause, it simplifies SQL queries and enhances readability, making it a key component of SQL query optimization for data retrieval and database manipula4 min readPostgreSQL - HAVING clauseThe HAVING clause in PostgreSQL is an essential feature for filtering grouped data that has been aggregated using functions like SUM(), COUNT(), AVG(), and others. Unlike the WHERE clause, which filters rows before aggregation, the HAVING clause is used to filter results after the grouping and aggre4 min readPostgreSQL - GROUP BY clauseThe GROUP BY clause in PostgreSQL is an essential tool that allows us to group rows that share the same values in one or more columns. This powerful functionality is commonly used to perform aggregate calculations such as SUM(), COUNT(), AVG(), and more, enabling us to summarize data efficiently. In4 min readPostgreSQL - LIKE operatorIn PostgreSQL, the LIKE operator is an essential tool for pattern matching in SQL queries. Whether we're dealing with large datasets or searching for specific string patterns, this operator provides a powerful way to filter and retrieve data based on partial matches. By Using wildcard search techniq5 min readPostgreSQL - BETWEEN OperatorThe PostgreSQL BETWEEN operator is an essential tool for filtering data within a specific range. Often used in the WHERE clause of SELECT, INSERT, UPDATE, and DELETE statements, this operator simplifies range-based conditions, making queries faster and easier to read. In this article, we will explai3 min readTable OperationsPostgreSQL - CREATE TABLEIn PostgreSQL, the CREATE TABLE statement is used to define a new table within a database. It allows us to specify the table's structure, including column names, data types, and constraints, ensuring data integrity and consistency. Understanding the PostgreSQL table creation process is essential for5 min readPostgreSQL - SELECT INTOThe PostgreSQL SELECT INTO statement allows users to create a new table directly from the result set of a query. This command is ideal for duplicating or organizing data from an existing table into a new one for further analysis. SELECT INTO does not return data to the client but saves it in a new t4 min readPostgreSQL - CREATE SEQUENCEIn database management, generating unique identifiers is vital for data integrity, and PostgreSQL provides a powerful feature called CREATE SEQUENCE to solve this. This command allows developers to create a sequence that automatically generates unique numeric values. In this article, we will explore4 min readPostgreSQL - ALTER TABLEIn PostgreSQL, the ALTER TABLE statement is a powerful and essential tool that allows us to modify the structure of an existing table to meet evolving database needs. With PostgreSQL ALTER TABLE, we can perform various modifications on the table without disrupting the ongoing operations of our datab6 min readPostgreSQL - ADD COLUMNIn PostgreSQL, the ADD COLUMN statement is a powerful command used to modify an existing database table by adding one or more new columns. This feature is important for adapting table structures to meet evolving data requirements, and it plays a key role in database management and optimization.In th4 min readPostgreSQL - DROP COLUMNIn PostgreSQL, there are instances where you might need to remove unnecessary or obsolete columns from your database tables. The DROP COLUMN clause in the ALTER TABLE statement allows you to do this with ease. When you drop a column from a table, PostgreSQL automatically removes any associated index2 min readPostgreSQL - Rename TableRenaming a table in PostgreSQL is a common task that can be quickly done using the RENAME clause in combination with the ALTER TABLE statement. This article will walk you through the process of renaming an existing table in PostgreSQL, explaining the syntax, and providing a detailed example.SyntaxAL2 min readPostgreSQL - DROP TABLEIn PostgreSQL, the DROP TABLE statement is a powerful and permanent command used to delete one or more tables from a database. Since this operation cannot be undone, it is essential to understand how to use it safely and to be aware of its options to prevent accidental data loss. In this article, we5 min readPostgreSQL - TRUNCATE TABLEIn PostgreSQL, the TRUNCATE TABLE statement provides a quick and efficient way to remove all data from large tables, freeing up storage space instantly. Unlike the DELETE statement, which removes rows one by one and logs each deletion, TRUNCATE TABLE is optimized for performance, especially with lar4 min readPostgreSQL - Copy a TableThis article will focus on copying an existing table to a new table in PostgreSQL. This might come in handy while creating new tables that would either have the same data or data of the same table with certain operations performed on them.Ways to Copy a TableWe will discuss the following 3 cases to3 min readPostgreSQL - Comparing TablesComparing tables in PostgreSQL is a common task when you need to identify differences between datasets. This can be especially useful when you are merging tables, validating data, or performing quality checks. In this article, we'll explore two of the most commonly used techniques for comparing tabl3 min readPostgreSQL - Show TablesIn PostgreSQL, viewing tables is an essential task for managing and organizing our database. Although PostgreSQL does not support the SHOW TABLES command like MySQL, it offers alternative commands like \dt in the psql tool, which helps users list all tables within a specific databaseIn this article,4 min readModifying DataPostgreSQL - INSERTPostgreSQL INSERT statement is one of the fundamental SQL commands used to add new rows to a specified table within a PostgreSQL database. This command allows users to insert data efficiently, whether for a single record or multiple records at once. With the PostgreSQL INSERT INTO clause, we can spe4 min readPostgreSQL - Insert Multiple Values in Various RowsPostgreSQL, one of the most popular relational database management systems (RDBMS), is widely used for storing structured data in a tabular format, much like MySQL. In relational databases, data is stored in tables where each row represents a record and each column represents an attribute. One of th3 min readPostgreSQL UPDATE StatementThe PostgreSQL UPDATE statement is an important SQL command used to modify existing data in one or more rows of a table. It allows users to update specific columns or multiple columns at once, using conditions defined in the WHERE clause. This command is highly flexible, enabling dynamic data manage5 min readPostgreSQL - DELETEThe DELETE statement is a key command in PostgreSQL used to remove existing records from a table. By using DELETE, you can eliminate unwanted or outdated records, helping keep your database organized and up to date.In this article, we will explore the DELETE statement, its syntax, and some practical4 min readPostgreSQL - UpsertUPSERT in PostgreSQL is a powerful database operation that merges the functionalities of INSERT and UPDATE into a single command. This operation allows users to either insert a new row into a table or update an existing row if it already exists.Also, making it essential for efficient data management4 min readConditionalsPostgreSQL - CASEIn PostgreSQL, the CASE expression allows you to perform conditional operations within your SQL queries. It evaluates a list of conditions and returns a result when the first condition is met. If no conditions are met, it returns the result specified in the ELSE clause.Let us better understand the C3 min readPostgreSQL COALESCEHandling NULL values effectively is important in database management, and PostgreSQL offers a powerful function called COALESCE to address this issue. The COALESCE function returns the first non-null argument among its parameters, making it particularly useful in SELECT statements.In this article, w5 min readPostgreSQL - NULLIF() FunctionEffectively handling NULL values is important in database management, especially for ensuring data integrity and avoiding errors. PostgreSQL offers several powerful functions, such as NULLIF and COALESCE, to help manage NULL and empty values efficiently. In this article, we will guide us through the4 min readPostgreSQL - CASTThe PostgreSQL CAST function provides an efficient way to convert data types in PostgreSQL, which is important when ensuring data is in the correct format for storage, calculations, or comparisons. In PostgreSQL, we can use CAST to transform data between various data types, such as converting string3 min readControl FlowPostgreSQL - IF StatementPostgreSQL IF statement is an essential tool for implementing conditional logic within SQL queries and stored procedures. It allows developers to execute different actions based on specific conditions and enhances the flexibility of database operations. In this article, we will explore various Postg5 min readPostgreSQL - CASE StatementIn PostgreSQL, CASE statements provide a way to implement conditional logic within SQL queries. Using these statements effectively can help streamline database functions, optimize query performance, and provide targeted outputs. This guide will break down the types of CASE statements available in Po4 min readPostgreSQL - Loop StatementThe LOOP statement in PL/pgSQL is used to create an unconditional loop that executes a block of code repeatedly until a RETURN or EXIT statement terminates it. This article will help you understand the syntax and usage of the LOOP statement, and provide examples to display its application.Let us get3 min readPostgreSQL - While LoopsWhen working with PostgreSQL, knowing how to efficiently use loops can be essential for running iterative operations. PostgreSQL’s WHILE loop allows developers to repeatedly execute a block of code as long as a specified condition remains true. PostgreSQL provides the loop statement which simply def4 min readPostgreSQL - Exit StatementIn PostgreSQL, the EXIT statement is a powerful tool used to terminate loops and blocks of code. This functionality is essential for managing control flow within your PostgreSQL scripts, allowing for more efficient and readable code. Let us get a better understanding of the usage of the EXIT stateme3 min readPostgreSQL - ContinueThe CONTINUE statement in PostgreSQL is used to prematurely skip the current iteration of a loop and proceed directly to the next iteration. This functionality applies to all types of loops, including unconditional loops, WHILE loops, and FOR loops.Let us get a better understanding of the CONTINUE s3 min readTransactions & ConstraintsPostgreSQL - TransactionsA transaction in database terminology is not a new concept. Similar to familiar terms such as "cash transaction" in banking, a transaction in the context of databases like PostgreSQL is a unit of work that ensures data integrity and consistency. Transactions are fundamental when you need to add, del4 min readPostgreSQL - COMMITThe COMMIT command in PostgreSQL is important for saving the changes made during a transaction. Without executing a COMMIT, all the data manipulation operations performed within the transaction will be lost once the session ends. It ensures that the changes made to the database are permanent and vis4 min readPostgreSQL - Primary KeyA primary key in PostgreSQL is a column (or a set of columns) that uniquely identifies each row in a table. It is an important component for ensuring data integrity and plays an important role in database normalization. When we define a primary key in PostgreSQL, the database automatically creates a4 min readPostgreSQL - Foreign KeyForeign keys play a crucial role in relational databases by establishing relationships between tables and safeguarding data integrity. In this PostgreSQL foreign key tutorial, we'll cover how foreign keys work, their importance and how to create them. We will also learn about foreign key constraints5 min readPostgreSQL - CHECK ConstraintIn PostgreSQL, the CHECK constraint is a powerful tool used to enforce data integrity by specifying that a value in a column must meet a specific requirement. The CHECK constraint uses a Boolean expression to evaluate the values before performing an insert or update operation on the column. If the v2 min readPostgreSQL - UNIQUE ConstraintIn PostgreSQL, the UNIQUE constraint is a powerful tool used to ensure that values stored in a column or a group of columns are unique across rows in a table. This constraint is essential for maintaining data integrity, especially when certain data should not be duplicated. For instance, if you're s3 min readPostgreSQL - NOT NULL ConstraintIn PostgreSQL, the NOT NULL constraint is a fundamental feature to ensure that a column cannot contain NULL values. NULL represents unknown or missing information in databases, distinct from an empty string or the number zero. For example, if you ask someone for their email address and they don’t kn3 min readJOINS & SchemasPostgreSQL - JoinsThe PostgreSQL JOIN statement is a powerful tool for combining data or rows from one or more tables based on a common field between them. These common fields are typically the primary key in the first table and the foreign key in the other table(s). By using different types of JOINs, we can perform5 min readPostgreSQL - LEFT JOINIn PostgreSQL, the LEFT JOIN (or LEFT OUTER JOIN) is a powerful tool that allows you to merge data from two tables based on a related column. With a LEFT JOIN, you get all records from the "left" table and matching records from the "right" table. If there’s no match in the right table, NULL values w5 min readPostgreSQL - INNER JOINIn PostgreSQL the INNER JOIN keyword selects all rows from both the tables as long as the condition satisfies. This keyword will create the result-set by combining all rows from both the tables where the condition satisfies i.e value of the common field will be the same. Syntax: SELECT table1.column2 min readPostgreSQL - FULL OUTER JOINIn PostgreSQL, the FULL OUTER JOIN is a powerful feature that combines the effects of both LEFT JOIN and RIGHT JOIN. This join operation retrieves all rows from both tables involved in the join, including unmatched rows from each table. For any unmatched rows, PostgreSQL fills the result with NULL v4 min readPostgreSQL - SELF JOINIn PostgreSQL, a SELF JOIN is a powerful technique that allows us to join a table with itself. This type of join is particularly useful for comparing rows within the same table, such as establishing hierarchical relationships or identifying duplicate records. Unlike other joins, there is no specific4 min readPostgreSQL - SchemaPostgreSQL is a powerful, open-source relational database management system (RDBMS) that is widely used for managing data. One of the most important concepts in PostgreSQL is the schema. A schema is a way of organizing database objects like tables, views, indexes, functions, and data types. In this5 min readPostgreSQL - CREATE SCHEMAPostgreSQL provides the CREATE SCHEMA statement to create a new schema in a database. By creating schemas, users can effectively separate data into logical groups, making it easier to manage and access information. Schemas also enhance security by controlling object visibility and permissions, allow5 min readPostgreSQL - DROP SCHEMAPostgreSQL offers a powerful schema management system, allowing database administrators to organize and manage objects within specific schemas. The DROP SCHEMA statement in PostgreSQL provides a straightforward way to delete entire schemas and the associated objects, making it a valuable tool for da4 min readPostgreSQL - ALTER SCHEMAIn PostgreSQL, the ALTER SCHEMA statement is a powerful tool that allows you to modify the definition of an existing schema. By understanding how to use ALTER SCHEMA effectively is crucial for managing your database schemas. This article will provide a detailed exploration of the ALTER SCHEMA statem3 min read Like