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Using Parameters

What is a Parameter?

Parameter is a placeholder for a variable that contains a value of some type that is passed to a database server along with the SQL text at the query execution time. Also parameter can hold values returned by a server after query or stored procedure execution.

You can benefit from using of parameters in the following situations:

• When you execute a query multiple times with different input values
• When you debug a query from your application code

Adding Parameters to a Query Text

Parameters are declared using ‘:’ prefix followed by name of the parameter.

For example:

SELECT
  employee.*
FROM
  hr.employee
WHERE
  employee.title = :job AND
  employee.vacation_hours <= :level

:job and :level are parameters in this query.

Modifying Parameter Values and Types

When you run a query that contains parameters with empty values, you will be automatically prompted to initialize them.

To set parameter values and types select Edit Parameters command from the Devart-SQL toolbar or from the dbForge SQL menu. In open Edit Parameters dialog box set parameters’ type, value, and other properties.

Note

When you execute a query with preset parameter values, you will not be automatically prompted to edit them. To edit parameters, press F8 or select Edit Parameters on the Devart-SQL toolbar.

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