SQL quotes

Yes, it does matter whether you use single quotes or double quotes in PostgreSQL, as they serve different purposes:

1. Single quotes ('): Used to denote string literals.
   For example:

   SELECT * FROM table_name WHERE column_name = 'some_value';

   Here, 'some_value' is a string literal.

2. Double quotes ("): Used to denote identifiers such as column names, table names, or other database object names.
   For example:

   SELECT * FROM "Table_Name" WHERE "Column_Name" = 'some_value';

   In this case, "Table_Name" and "Column_Name" are identifiers, and they are case-sensitive when double-quoted.

Key Notes:

• String literals must always use single quotes. Using double quotes for strings will result in a syntax error.
• If you don’t quote identifiers (e.g., column names), PostgreSQL treats them as case-insensitive by default. For example, column_name and COLUMN_NAME are treated the same. However, when you use double quotes, the identifiers become case-sensitive. So "Column_Name" and "column_name" would be treated as different identifiers.
• Avoid using double quotes for identifiers unless necessary (e.g., you want case sensitivity or your identifier has spaces or special characters).

Example of Incorrect Usage:

SELECT * FROM table_name WHERE column_name = "some_value"; -- Error

PostgreSQL will throw a syntax error because some_value in double quotes is interpreted as an identifier, not a string.

Correct Usage:

SELECT * FROM table_name WHERE column_name = 'some_value'; -- Correct