How Can I Assign a Variable a Value from a SQL Query?

Setting a Variable from a SQL Query

As you've encountered, directly using the declare statement in the given context may result in errors. This article demonstrates effective approaches to assign values to a variable based on a SQL query using two methods: SELECT and SET.

Using SELECT

The following snippet employs the SELECT statement to set the variable:

SELECT @ModelID = m.modelid 
FROM MODELS m
WHERE m.areaid = 'South Coast'

Using SET

Alternatively, you can use the SET statement:

SET @ModelID = (SELECT m.modelid 
                  FROM MODELS m
                 WHERE m.areaid = 'South Coast');

Using the Variable

Once the variable is set, you can retrieve its value using SELECT or incorporate it into your code as needed:

SELECT @ModelID

Considerations

Be cautious when dealing with queries that return multiple values. SELECT will assign the variable the last value returned, potentially leading to logical errors. SET, on the other hand, will only return an error if the query lacks a semicolon at its end. Ensure that your queries adhere to best practices and return unique values when working with variables.

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