In PostgreSQL, the MAX function is used to return the maximum value among a set of values. The syntax of the MAX function is as follows: SELECT MAX(column_name) FROM table_name; column_name is the name of the column from which you want to find the maximum value, and table_name is the name of the table in…
In PostgreSQL, the TRUNCATE command is used to remove all data from a table while preserving the structure of the table. TRUNCATE statement is faster than the DELETE statement to delete all the rows of a table. Below is the syntax of the TRUNCATE command: TRUNCATE TABLE table_name; In the above command table_name is the…
To add a new column to a table in PostgreSQL, you can use the ALTER TABLE statement with the ADD COLUMN clause. Syntax is as shown below: ALTER TABLE table_name ADD COLUMN column_name data_type [column_constraints]; Where: Below is an example to add a new column “email” of data type varchar(255) to a table “users”. ALTER…
The PostgreSQL UPDATE statement can be used to modify existing records in a table. The basic syntax of the UPDATE statement is as follows: UPDATE table_name SET column1 = value1, column2 = value2, … WHERE conditions; Below is an example to demonstrates the usage of the UPDATE statement: Consider a table named “employees” with the…
To insert data into a table in PostgreSQL, you can use the INSERT statement. Below is the syntax: INSERT INTO table_name (column1, column2, column3, …) VALUES (value1, value2, value3, …); Below is an example of inserting data into a table named “employees” with columns “id”, “name”, and “age”: INSERT INTO employees (name, department, salary) VALUES…
PostgreSQL supports unique constraints to ensure that the values in a particular column ( or set of columns ) are unique across all rows in a table. Unique constraint can be defined on one or more columns of a table. To create a unique constraint in PostgreSQL, you can use the UNIQUE keyword followed by…
Below is the sql command syntax to create a table in PostgreSQL database: CREATE TABLE table_name ( column1 datatype1 constraint1, column2 datatype2 constraint2, column3 datatype3 constraint3, … ); Below is an example of how to create a table in PostgreSQL database with two columns: CREATE TABLE employees ( employee_id integer, employee_name text ); Above sql…