A query to retrieve database values for a first subset of table columns in a database table is determined. Runtime column selection variables are set up to identify the first subset of table columns for data retrieval, and are dynamically bound to a prepared query statement with single-column query statements joined by interstitial union operators. Each single-column query statement in the prepared query statement specifies a single-column query directed to a corresponding table column with a corresponding predicate to be bound at runtime dynamically with a corresponding portion of the one or more runtime column selection variables. The predicate is evaluated to be true or false in dependence on whether the corresponding table column is in the first subset of table columns. The prepared query statement is executed to retrieve database values for the first subset of table columns in the database table.