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Variable binding
Every org.jooq.QueryPart must implement the accept(Context<?>) method. This Context has two purposes (among many others):
- It provides some information about the "state" of the variable binding in process.
- It provides a common API for binding values to the context's internal java.sql.PreparedStatement
An overview of the org.jooq.BindContext API is given here:
// This method provides access to the PreparedStatement to which bind values are bound PreparedStatement statement(); // These methods provide convenience to delegate variable binding BindContext bind(QueryPart part) throws DataAccessException; BindContext bind(Collection<? extends QueryPart> parts) throws DataAccessException; BindContext bind(QueryPart[] parts) throws DataAccessException; // These methods perform the actual variable binding BindContext bindValue(Object value, Class<?> type) throws DataAccessException; BindContext bindValues(Object... values) throws DataAccessException;
Some additional methods are inherited from a common org.jooq.Context, which is shared among org.jooq.RenderContext and org.jooq.BindContext. Details are documented in the previous chapter about SQL rendering
An example of binding values to SQL
A simple example can be provided by checking out jOOQ's internal representation of a (simplified) CompareCondition. It is used for any org.jooq.Condition comparing two fields as for example the AUTHOR.ID = BOOK.AUTHOR_ID condition here:
-- [...] WHERE AUTHOR.ID = ? -- [...]
This is how jOOQ binds values on such a condition:
@Override
public final void bind(BindContext context) throws DataAccessException {
// The CompareCondition itself does not bind any variables.
// But the two fields involved in the condition might do so...
context.bind(field1).bind(field2);
}
See the manual's sections about custom QueryParts and plain SQL QueryParts to learn about how to write your own query parts in order to extend jOOQ.
