User-Defined Variables

The @ sign precedes user-defined variables in MySQL, which may be set and retrieved at any time throughout a session. They are commonly used to temporarily store values and transfer them across queries.

Process:

  • Set a user-defined variable with the SET command.
  • Access the variable in subsequent queries in the same session.

— Setting a User-Defined Variable

SET @user_var = 100;

— Accessing the User-Defined Variable

SELECT @user_var;

User Defined Variables vs Local Variables in MySQL

In MySQL, both user-defined and local variables are important for storing temporary data during SQL query execution. Understanding the distinctions and applications of each type is critical for effective query execution and attaining the appropriate results.

This article delves into the differences between user-defined variables and local variables in MySQL, offering insights into their use and instances in which one may be favored over the other.

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User-Defined Variables

The @ sign precedes user-defined variables in MySQL, which may be set and retrieved at any time throughout a session. They are commonly used to temporarily store values and transfer them across queries....

Local Variables

In MySQL, local variables are declared with the DECLARE command within a stored program (such as a stored procedure or function). They have a specific scope inside the block in which they are stated....

Example of User-defined Variables and Local Variables in MySQL

Example 1: User-Defined Variable...

Conclusion

Learning the differences between MySQL’s user-defined variables and local variables is critical for developing efficient and successful SQL queries. User-defined variables are used to hold temporary values during a session, allowing for data manipulation and exchange between queries. Local variables, which are declared within stored procedures or functions, provide a more constrained scope for encapsulating functionality and ensuring data integrity within a given block....