sql:update and sql:column
sql:update performs an SQL UPDATE statement. This causes a set of rows to be selected from a given table; columns
identified in a child
sql:column element are then updated with new values.
The attributes are as follows:
The database connection.
This is mandatory, the value is an expression, which must evaluate to a database connection
object as returned by
The table to be updated.
This is mandatory, and the value must be known statically (it cannot be defined as an attribute value template).
The conditions to be applied (the contents of the WHERE clause of the select statement).
This is optional, if present the value is an attribute value template whose value is a SQL conditional expression.
If omitted, all rows in the table are updated.
sql:column is used as a child element of
sql:update, and identifies the name and value of a column
to be included in the UPDATE statement. The name of the column is identified by the
the value may be indicated either by evaluating the expression contained in the
select attribute, or
as the expanded contents of the
sql:column element. The value is always interpreted as a String.
(Remember this is purely a demonstration of extensibility, in a real system there would be a need to
cater for SQL columns of other data types).