What is the Difference Between variable and parameter in SQL? with Proper Definition and Brief Explanation

The main difference between variable and parameter in SQL is that the variable helps to hold a single data value of a specific type, while the parameter helps to exchange data between stored procedures and functions.

SQL (structured query language) is a computer language for storing, managing, and retrieving data in relational databases. RDBMS like MSSQL uses variables and parameters, and we can refer to them anywhere in a SQL procedure statement.

Key areas covered

1. What is the variable in SQL
– Definition, Functionality
2. What is the parameter in SQL
– Definition, Functionality
3. What is the difference between variable and parameter in SQL?
– Comparison of key differences

Key terms

Variable, Parameter, SQL

What is the variable in SQL

Variable in SQL is an object that can hold a single data value of a specific type. Also, it is possible to use it as a counter to count the number of iterations in a loop control structure. It also helps to keep a data value to be tested by checking the flow statement. Also, it helps to save a data value that is returned from a stored procedure return code or function return value.

The DECLARE statement helps initialize a variable. The variable must have a name to identify it. Therefore, it begins with a single @ as the first character. The programmer must then assign a system-supplied or user-defined data type and a length to that variable. Generally, a variable is used in stored procedures where it is declared ..

An example is the following. The MyResult is a variable of type int.

DECLARE @MyResultint;

It is also possible to declare multiple variables as follows. Declare three variables: Name, Surname and Age.

DECLARE @FirstName varchar (20), @LastName varchar (20), @Age int;

When you first declare the variable, its value is set to NULL. Also, to assign a value to a variable, the programmer can use the SET statement.

Use Student DB;

DECLARE @FirstNamevarchar (20), @Age into;

SET @FirstName = “Ann”;

SET @Age = 20;

SELECT First Name, Last Name, City, Age from Student Details

WHERE Name = @ First Name or Age = @ Age;

The above SQL script declares two variables: Name and Age. SET statements assign them values. Finally, the select statement helps to get the values from the student details table using those variables.

What is the parameter in SQL

A parameter in SQL helps to exchange data between stored procedures and functions. With the help of input parameters, the caller can pass a data value to the stored procedure or function. Whereas, with the help of the output parameters, the stored procedure can pass a data value to the caller. Additionally, each stored procedure returns an integer return code to the caller. However, if the stored procedure does not explicitly set a value for the return code, it will return 0.

CREATION PROCEDURE MyProcedure @EmployeeID INT, @MaxTotal INT OUTPUT

WHAT

DECLARE @ErrorSave INT

Set @ErrorSave = 0

Select First Name, Last Name, City FROM HR.table1

WHERE EmployeeID = @EmplyeeID

YES (@@ ERROR <> 0)

SET @ErrorSave == @@ ERROR

SELECT @MaxTotal = MAX (TotalDue)

FROM Sales.table2;

YES (@@ ERROR <> 0)

SET @ErrorSave = @@ ERROR

BACK @ErrorSave

The MySample is a procedure that takes an input parameter and returns an output parameter. The select statement is executed using the @EmployeeID input parameter. Then any non-zero value is stored in @ErrorSave. The @MaxTotal output parameter is then mapped with the MAX (TotalDue). Finally, the 0 will return if the SELECT statement has an error. If not, the last error will come back.

Difference between variable and parameter in SQL

Definition

A variable in SQL is an object that can contain a single data value of a specific type. In contrast, a parameter in SQL is an object that can exchange data between stored procedures and functions. These definitions explain the fundamental difference between variable and parameter in SQL.

Use

The main difference between variable and parameter in SQL is their usage. A variable in SQL helps to hold a single data value of a specific type, while a parameter in SQL helps to exchange data between functions and stored procedures.

conclusion

In conclusion, the main difference between variable and parameter in SQL is that variable helps to hold a single data value of a specific type, while parameter helps to exchange data between stored procedures and functions.

Reference:

1. “Variables (Transact-SQL)”. Microsoft Docs, Available here.
2. “Parameters”. Microsoft Docs, Available here.

Courtesy Image:

1. “156948” (CC0) via Pixabay