How to Properly Quote Identifiers and Values in SQL?

The use of backticks in SQL

Contrary to common misconception, the SQL standard does not recognize the backtick (`), also known as the "antisingle quote", as a special symbol. The standard mechanism for quoting identifiers in SQL is double quotes.

Use delimited identifiers

When necessary, you can enclose an identifier in double quotes to distinguish it from reserved keywords in a specific SQL implementation. This is especially useful for:

• The same identifier as the keyword (for example, "SELECT" and "WHERE")
• Identifiers containing spaces or other special characters

When to use quotation marks

For value:

• Always use single quotes (' ') to enclose string literals (for example, 'Hello World').
• Use double quotes (" ") to enclose values ​​that contain single quotes (for example, "'John & Mary'").

For field names:

• In general, avoid using quotes around field names.
• Use double quotes for field names that are the same as keywords or contain special characters (for example, "Order Date" or "My-Field").

Advantages of avoiding quotation marks

• Improve code readability and maintainability.
• Reduce case sensitivity issue.
• Easier to update code when SQL keywords or reserved words change.

Other notes

• Some DBMS (e.g. MySQL) allow single and double quotes to be used interchangeably. However, it is recommended to use double quotes for identifiers and single quotes for values.
• The backtick is recognized as a comment separator in some SQL implementations, but it is not standardized.

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