How to add a new column in PostgreSQL?

by hal.littel , in category: PHP Databases , 2 years ago

How to add a new column in PostgreSQL?

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2 answers

by giovanny.lueilwitz , a year ago

@hal.littel 

To add a new column to a table in PostgreSQL, you can use the ALTER TABLE statement and the ADD COLUMN clause. Here's the basic syntax:

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ALTER TABLE table_name
ADD COLUMN column_name data_type;


For example, to add a new column called email to a table called customers, you can use the following statement:

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ALTER TABLE customers
ADD COLUMN email VARCHAR(255);


This will add a new column called email to the customers table, with a data type of VARCHAR(255). You can replace VARCHAR(255) with any other data type that is supported by PostgreSQL.


You can also specify additional options when adding a new column, such as a default value or a constraint. For example, to add a new column called age to a table called employees, with a default value of 18, you can use the following statement:

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ALTER TABLE employees
ADD COLUMN age INT DEFAULT 18;


This will add a new column called age to the employees table, with a data type of INT and a default value of 18.


I hope this helps! Let me know if you have any questions.

Member

by denis , 8 months ago

@hal.littel 

To add a new column in PostgreSQL, you can use the ALTER TABLE statement with the ADD COLUMN clause. Here is the syntax:

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ALTER TABLE table_name 
ADD COLUMN column_name data_type;


For example, let's say you have a table named "employees" and you want to add a new column called "salary" of type numeric:

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ALTER TABLE employees
ADD COLUMN salary numeric;


You can also specify additional constraints such as default values, NOT NULL, and foreign key constraints if needed. Here are some examples:

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-- Add a column with a default value
ALTER TABLE employees
ADD COLUMN hire_date date DEFAULT current_date;

-- Add a column with a NOT NULL constraint
ALTER TABLE employees
ADD COLUMN email varchar(255) NOT NULL;

-- Add a column with a foreign key constraint
ALTER TABLE employees
ADD COLUMN department_id integer REFERENCES departments(department_id);


You can include multiple ADD COLUMN statements within a single ALTER TABLE statement if you want to add multiple columns at once.