Which data in sql needs to be quoted

In SQL, data that needs to be enclosed in quotes includes character data, date and time values, and NULL values. The purpose of quoting is to prevent SQL injection attacks and to identify the value as text, rather than an SQL command or function. However, when the data type is a number, Boolean, or enumeration value, quoting is not required.

Data that needs to be quoted in SQL

In SQL, the following types of data need to be enclosed in quotes :

• Character data: All character data, including text, words, or phrases.
• Date and Time: Date and time values.
• NULL value: A value indicating that no data exists.

Specific examples that require quotation marks

• String: 'John Doe'
• Date: '2023-03- 08'
• Time: '14:30:00'
• NULL Value: 'NULL'

Why add quotation marks

SQL treats values ​​within quotes as text and does not interpret them as SQL commands or functions. This helps prevent SQL injection attacks, in which a malicious user corrupts or manipulates a database by entering malicious code into an input field.

When quotation marks are not required

Quotation marks are not required in the following situations:

• Numeric data types such as integers and floating point numbers .
• Boolean values ​​(TRUE and FALSE).
• Values ​​in enumerations and collections.

Exceptions

In some cases, quoting is not required even though the data type would normally require quoting. For example:

• When values ​​are stored in a column with a single quote (') as its character delimiter.
• When the value is represented using an escape sequence, such as the escape character ('\') followed by a quote ('').

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