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postgres insert new row advance count with code examples

Ajay Kemparaj

In database management, the ability to insert new rows into a database table is one of the most fundamental functionalities. PostgreSQL, a widely used open-source relational database management system, offers advanced capabilities for inserting new rows into a table, including the ability to insert multiple rows at once, insert conditional rows, and track the number of inserted rows. In this article, we'll look at how to perform advanced row insertion in PostgreSQL, including code examples.

Inserting a Single Row

To insert a single row into a PostgreSQL table, we can use the following SQL statement:

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);

For example, let's say we have a table called "employees" with the following columns: "id", "name", "age", "salary", and "department". To insert a new row into this table, we could use the following SQL statement:

INSERT INTO employees (name, age, salary, department) VALUES ('John Smith', 35, 60000, 'Sales');

This statement will insert a new row into the "employees" table with the name "John Smith", age 35, salary 60000, and department "Sales".

Inserting Multiple Rows

If we need to insert multiple rows into a table at once, we can use the following SQL statement:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...),
       (value1, value2, value3, ...),
       (value1, value2, value3, ...),
       ...;

For example, to insert three new employees into the "employees" table, we could use the following SQL statement:

INSERT INTO employees (name, age, salary, department)
VALUES ('Jane Doe', 28, 50000, 'Marketing'),
       ('Bob Johnson', 42, 80000, 'Finance'),
       ('Sally Wilson', 31, 55000, 'HR');

This statement will insert three new rows into the "employees" table with the respective values for name, age, salary, and department.

Inserting Conditional Rows

PostgreSQL provides the ability to insert new rows into a table conditionally using the "INSERT INTO SELECT" statement. This statement allows us to select data from another table or a subquery and insert the selected data into a table, with the option to apply conditions to the selected data.

Here's an example of how to use the "INSERT INTO SELECT" statement to insert rows into a table conditionally:

INSERT INTO table_name (column1, column2, column3, ...)
SELECT column1, column2, column3, ...
FROM other_table
WHERE condition;

For example, let's say we have two tables, "employees" and "temp_employees". The "employees" table contains all current employees, while the "temp_employees" table contains new hires who are still in a probationary period. We want to conditionally insert only those new hires who meet certain criteria into the "employees" table. We could use the following SQL statement:

INSERT INTO employees (name, age, salary, department)
SELECT name, age, salary, department
FROM temp_employees
WHERE probation_period_end < '2022-01-01';

This statement will select all new hires from the "temp_employees" table whose probation period ends before January 1st, 2022, and insert them into the "employees" table.

Tracking the Number of Inserted Rows

PostgreSQL provides the ability to track the number of rows that are affected by an SQL statement, including insertions. To track the number of inserted rows, we can use the "RETURNING" clause in our SQL statement.

Here's an example of how to track the number of inserted rows:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...)
RETURNING count(*);

For example, to track the number of new employees inserted into the "employees" table, we could use the following SQL statement:

INSERT INTO employees (name, age, salary, department)
VALUES ('Jane Doe', 28, 50000, 'Marketing'),
       ('Bob Johnson', 42, 80000, 'Finance'),
       ('Sally Wilson', 31, 55000, 'HR')
RETURNING count(*);

This statement will insert three new employees into the "employees" table and return the number of rows inserted, which in this case will be 3.

Conclusion

PostgreSQL provides advanced capabilities for inserting new rows into a table, including the ability to insert multiple rows at once, insert conditional rows, and track the number of inserted rows. By leveraging these capabilities, you can write more efficient and effective SQL statements to manage your database tables.

here are some additional details and examples related to the previous topics:

Inserting Multiple Rows

In PostgreSQL, there are multiple ways to insert multiple rows into a table. One way involves using a subquery in the VALUES clause, like this:

INSERT INTO my_table (col1, col2, col3)
VALUES
    (SELECT col1, col2, col3 FROM other_table WHERE col1 = 123),
    (SELECT col1, col2, col3 FROM other_table WHERE col1 = 456),
    (SELECT col1, col2, col3 FROM other_table WHERE col1 = 789);

This statement will insert three rows into "my_table" based on the results of the subqueries. Another way to do this is by using the UNION operator, like this:

INSERT INTO my_table (col1, col2, col3)
SELECT col1, col2, col3 FROM other_table WHERE col1 IN (123, 456, 789);

This statement will also insert three rows into "my_table" based on the results of the subquery in the SELECT clause. Use whichever method you find most intuitive.

Inserting Conditional Rows

One way to conditionally insert rows into a table is by using the WHERE clause on the SELECT statement used in the INSERT INTO statement. For instance, let's say you have a table named "orders", and you want to insert rows into this table from a table named "orders_temp", but only for orders with a certain status:

INSERT INTO orders (order_id, order_date, order_total)
SELECT
    order_id,
    order_date,
    order_total
FROM orders_temp
WHERE order_status = 'pending';

This statement will insert only rows from "orders_temp" with order_status = 'pending' into "orders". Note that the columns being referred to in the SELECT clause should match up with the columns in the INSERT INTO clause.

Another way to insert conditionally is by injecting a conditional expression inside the VALUES clause. Here's an example:

INSERT INTO users (user_id, email, is_active)
VALUES 
    (10001, 'johndoe@example.com', TRUE),
    (10002, 'janedoe@example.com', FALSE),
    (10003, 'johnsmith@example.com', CASE WHEN age < 35 THEN TRUE ELSE FALSE END);

This statement will insert three rows into "users". The first two rows are inserted using static values in the VALUES clause, while the third row uses a conditional expression based on a column in the same table ("age").

Tracking the Number of Inserted Rows

The RETURNING clause can be used in other SQL statements besides INSERT INTO, such as UPDATE and DELETE statements. To get the count of updated rows, use "RETURNING COUNT(*)" or "RETURNING count_col_name". For DELETE statements, use "RETURNING *", as only one column (the primary key) is deleted. Here's an example for INSERT INTO:

INSERT INTO users (user_id, full_name, age)
VALUES 
    (10025, 'John Doe', 28),
    (10026, 'Jane Doe', 34),
    (10027, 'Bob Smith', 41)
RETURNING COUNT(*);

This statement will insert three rows into "users" and return the number of rows inserted (in this case, 3). Note that COUNT(*) could be replaced with another column name ("count" in this example) if the TABLE contains any such column.

Popular questions

  1. What is the syntax for inserting a single row in PostgreSQL?

The syntax for inserting a single row in PostgreSQL is:

INSERT INTO table_name (column1, column2, column3, ...) VALUES (value1, value2, value3, ...);
  1. How do you insert multiple rows at once in PostgreSQL?

To insert multiple rows at once in PostgreSQL, you can use the following syntax:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...),
       (value1, value2, value3, ...),
       (value1, value2, value3, ...),
       ...;
  1. How can you conditionally insert rows into a PostgreSQL table?

You can conditionally insert rows into a PostgreSQL table by using the "INSERT INTO SELECT" statement with a WHERE clause:

INSERT INTO table_name (column1, column2, column3, ...)
SELECT column1, column2, column3, ...
FROM other_table
WHERE condition;
  1. How do you track the number of rows inserted in PostgreSQL?

To track the number of rows inserted in PostgreSQL, you can use the RETURNING clause in your INSERT statement, like this:

INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...)
RETURNING count(*);
  1. Can you insert a conditional expression inside the VALUES clause while inserting rows in PostgreSQL?

Yes, you can insert a conditional expression inside the VALUES clause while inserting rows in PostgreSQL. Here's an example:

INSERT INTO users (user_id, email, is_active)
VALUES 
    (10001, 'johndoe@example.com', TRUE),
    (10002, 'janedoe@example.com', FALSE),
    (10003, 'johnsmith@example.com', CASE WHEN age < 35 THEN TRUE ELSE FALSE END);

This statement will insert three rows into "users". The third row uses a conditional expression based on a column in the same table ("age").

Tag

SQL-incrementing

Throughout my career, I have held positions ranging from Associate Software Engineer to Principal Engineer and have excelled in high-pressure environments. My passion and enthusiasm for my work drive me to get things done efficiently and effectively. I have a balanced mindset towards software development and testing, with a focus on design and underlying technologies. My experience in software development spans all aspects, including requirements gathering, design, coding, testing, and infrastructure. I specialize in developing distributed systems, web services, high-volume web applications, and ensuring scalability and availability using Amazon Web Services (EC2, ELBs, autoscaling, SimpleDB, SNS, SQS). Currently, I am focused on honing my skills in algorithms, data structures, and fast prototyping to develop and implement proof of concepts. Additionally, I possess good knowledge of analytics and have experience in implementing SiteCatalyst. As an open-source contributor, I am dedicated to contributing to the community and staying up-to-date with the latest technologies and industry trends.
Website https://www.linkedin.com/in/ajaykemparaj/
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