SQL Quotation Marks: Single vs. Double – When to Use Which?

The difference between single quotes and double quotes in SQL

In the world of SQL, the use of quotation marks often raises questions. Understanding the difference between single and double quotes is critical to operating your database accurately.

Single quotes

Single quotes are mainly used to separate strings in SQL queries. They contain characters that should be interpreted literally, not as symbols or variables. For example, to represent the string 'Hello', you would use 'Hello' in the SQL statement.

Double quotes

In contrast, using double quotes in SQL is generally uncommon. Their behavior may vary in different database systems. However, it is recommended to stick to the convention of using single quotes for string delimitation.

Other uses

Besides its primary use, single quotes can also be used to define column aliases in SQL. Column aliases allow you to temporarily rename columns during query execution. You can enclose the desired alias in single quotes, for example, use 'product_id' for the column 'PRODUCT.id'.

Recommended Practices

To ensure consistency and avoid potential errors, it is recommended to always use single quotes for string delimitation and column alias definitions. This practice conforms to established SQL conventions and minimizes the risk of unexpected behavior.

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