PostgreSQL LOWER() String Function

PostgreSQL LOWER() String Function

The PostgreSQL LOWER() function is used to convert all characters in a string to lowercase. This function is essential for standardizing text data and performing case-insensitive comparisons.

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Syntax

LOWER(string)

The LOWER() function has the following component:

• string: The string to be converted to lowercase.

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Example PostgreSQL LOWER() Queries

Let's look at some examples of PostgreSQL LOWER() function queries:

1. Basic LOWER() Example

SELECT LOWER('Hello, World!') AS lowercase_string;

This query converts the string 'Hello, World!' to lowercase, resulting in 'hello, world!'.

2. LOWER() with Mixed Case

SELECT LOWER('PostgreSQL LOWER Function') AS lowercase_string;

This query converts the string 'PostgreSQL LOWER Function' to lowercase, resulting in 'postgresql lower function'.

3. LOWER() with Column Values

SELECT id, name, LOWER(name) AS lowercase_name
FROM users;

This query retrieves the id, name, and the lowercase version of the name for each row in the users table.

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Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the LOWER() function to standardize text data.

Step 1: Creating a Table

This step involves creating a new table named users to store user data.

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    name TEXT
);

In this example, we create a table named users with columns for id and name.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the users table.

INSERT INTO users (name)
VALUES ('Alice'),
       ('Bob'),
       ('Charlie');

Here, we insert data into the users table.

Step 3: Using the LOWER() Function

This step involves using the LOWER() function to standardize the text data in the users table.

Basic LOWER()

SELECT LOWER('Hello, World!') AS lowercase_string;

This query converts the string 'Hello, World!' to lowercase.

LOWER() with Mixed Case

SELECT LOWER('PostgreSQL LOWER Function') AS lowercase_string;

This query converts the string 'PostgreSQL LOWER Function' to lowercase.

LOWER() with Column Values

SELECT id, name, LOWER(name) AS lowercase_name
FROM users;

This query converts the values in the 'name' column of the 'users' table to lowercase.

These queries demonstrate how to use the LOWER() function to standardize the text data in the users table, including basic usage and handling mixed case.

Conclusion

The PostgreSQL LOWER() function is a fundamental tool for standardizing text data by converting all characters in a string to lowercase. Understanding how to use the LOWER() function and its syntax is essential for effective text data manipulation in PostgreSQL databases.