1. PHP
- Single quotes
' '- Treat everything inside as plain text.
- Variables are not parsed.
- Escape sequences (like
\n) are not interpreted, except\\and\'.
$name = "Himanshu"; echo 'Hello $name'; // Output: Hello $name echo 'It\'s fine'; // Output: It's fine - Double quotes
" "- Variables are parsed/interpolated.
- Escape sequences are interpreted (
\n,\t, etc.).
$name = "Himanshu"; echo "Hello $name"; // Output: Hello Himanshu echo "Line1\nLine2"; // Output: // Line1 // Line2
✅ In PHP: Use single quotes when no variables or escape sequences are needed (faster & cleaner). Use double quotes when variable interpolation is required.
2. JavaScript
' 'and" "are functionally the same for strings.- No difference in variable interpolation (since JS uses
+for concatenation or template literals). - Just a stylistic choice.
let name = "Himanshu"; console.log('Hello ' + name); // Hello Himanshu console.log("Hello " + name); // Hello Himanshu - ✅ Prefer consistency in a project (many use single quotes).
- For interpolation, JS has template literals using backticks (` `):
console.log(`Hello ${name}`); // Hello Himanshu
3. Python
' 'and" "are exactly the same for strings.- Mainly a style preference (Python PEP8 allows both).
name = "Himanshu" print('Hello ' + name) # Hello Himanshu print("Hello " + name) # Hello Himanshu - Use triple quotes (
'''or""") for multi-line strings.
4. SQL
- Strings must be in single quotes
' '. - Double quotes
" "are often used for identifiers (table/column names).SELECT * FROM users WHERE name = 'Himanshu'; SELECT "columnName" FROM "users";
✅ Summary:
- PHP → Big difference (interpolation & escape sequences).
- JavaScript & Python → No difference, just style.
- SQL → Single = string, Double = identifiers.