/**
* Build the select statement for selecting the locator
*/
private SQLSelectStatement buildSelectStatementForLocator(WriteObjectQuery writeQuery, DatabaseCall call, AbstractSession session) {
SQLSelectStatement selectStatement = new SQLSelectStatement();
Vector tables = writeQuery.getDescriptor().getTables();
selectStatement.setTables(tables);
//rather than get ALL fields from the descriptor, only use the LOB-related fields to build the minimal SELECT statement.
selectStatement.setFields(call.getContexts().getFields());
//the where clause setting here is sufficient if the object does not map to multiple tables.
selectStatement.setWhereClause(writeQuery.getDescriptor().getObjectBuilder().buildPrimaryKeyExpressionFromObject(writeQuery.getObject(), session));
//need pessimistic locking for the locator select
selectStatement.setLockingClause(ForUpdateClause.newInstance(ObjectBuildingQuery.LOCK));
if (tables.size() > 1) {
//the primary key expression from the primary table
Expression expression = selectStatement.getWhereClause();
//additional join from the non-primary tables
Expression additionalJoin = writeQuery.getDescriptor().getQueryManager().getAdditionalJoinExpression();
if (additionalJoin != null) {
expression = expression.and(additionalJoin);
}
//where clause now contains extra joins across all tables
selectStatement.setWhereClause(expression);
}
//normalize the statement at the end, such as assign alias to all tables, and build sorting statement
selectStatement.normalize(session, writeQuery.getDescriptor());
return selectStatement;
}