The <sql:param> tag is a JSTL SQL tag used to specify a parameter for an SQL query. The tag takes two attributes: value and type.

The value attribute specifies the value of the parameter, and the type attribute specifies the SQL type of the parameter.

The syntax of the <sql:param> tag is as follows:

<sql:param value="paramValue" type="sqlType" />

where paramValue is the value of the parameter, and sqlType is the SQL type of the parameter.

For example, the following JSP code retrieves all orders for a specific customer using a parameter:

<sql:setDataSource
  var="myDataSource"
  driver="com.mysql.jdbc.Driver"
  url="jdbc:mysql://localhost/mydatabase"
  user="myuser"
  password="mypassword" />

<sql:query dataSource="${myDataSource}">
  SELECT *
  FROM orders
  WHERE customer_id = ?
  ORDER BY order_date
  <sql:param value="${paramValue}" type="INTEGER" />
</sql:query>

In this example, the value attribute is set to ${paramValue}, which is the parameter value obtained from a variable or an expression, and the type attribute is set to "INTEGER", which is the SQL type of the parameter.

Note that the sql tag library must be imported at the beginning of the JSP page using the following tag:

<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>