Apprendre Introduction to String Functions

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In this module, you will explore a wide range of SQL functions designed to help you transform and analyze data efficiently. You will work with different categories of functions, including string functions for handling text, date and time functions for managing temporal data, numeric functions for calculations, logical functions for conditional operations, null functions for handling missing values, and JSON functions for working with structured data. These functions are essential for cleaning, standardizing, and extracting valuable insights from your data directly within SQL, making your queries more powerful and allowing you to solve real-world data problems with ease.

When working with text data in SQL, string functions are essential tools that let you transform, analyze, and extract information from character fields. These functions help you clean up messy data, standardize text formats, and create new values based on existing information. Whether you need to change the case of names, count the number of characters in an email address, or build custom strings for reports, string functions make these tasks simple and efficient.


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-- Transform and analyze customer names using string functions
SELECT
  name,
  UPPER(name) AS name_uppercase,
  LOWER(name) AS name_lowercase,
  LENGTH(name) AS name_length
FROM customers;

You can combine multiple string functions in a single query to perform advanced text processing. For instance, you might want to convert a name to lowercase and then count its characters, or standardize email addresses by joining different pieces of data together. By nesting and chaining functions, you gain powerful ways to reshape and analyze your text data directly within SQL.


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-- Create custom email usernames by combining and extracting strings
SELECT
  name,
  CONCAT(LOWER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, POSITION(' ' IN name) + 1, 5))) AS custom_username
FROM customers;

1. Which function changes all characters in a string to uppercase?

2. Which SQL function extracts a substring from a given string?

3. Fill in the blanks to select the length of each customer's name after converting it to lowercase.

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Section 1. Chapitre 1

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Section 1. Chapitre 1