What does @ in sql mean?

The @ symbol in SQL is used to specify variable parameters in a query, which is helpful to improve code readability, prevent SQL injection attacks, and improve performance. Syntax: @parameter_name, where parameter_name is the name of the parameter.

The meaning of the @ symbol in SQL

In SQL, the @ symbol is used to specify a parameter. Parameters are the mutable part of the query and can be replaced by different values while the query is executed.

Purpose

Using the @ symbol has several benefits:

• Improve code readability:Enable query Easier to read and understand because the parameters are separated from the actual values.
• Prevent SQL injection attacks:By passing user input as parameters, you can prevent malicious users from modifying the query and performing unauthorized operations.
• Improve performance:By using parameterized queries, the database can precompile the query and store it in the cache, thus improving performance.

Syntax

The syntax for specifying parameters using the @ symbol is as follows:

@parameter_name

whereparameter_nameis the name of the parameter .

Example

The following is an example query that uses the @ symbol to specify a parameter named@age:

SELECT * FROM users WHERE age > @age;

When executing this query, different@agevalues can be provided to find users of different age groups. For example:

-- 查找年龄大于 30 岁的人 SELECT * FROM users WHERE age > 30; -- 查找年龄大于 25 岁的人 SELECT * FROM users WHERE age > 25;

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