Class MapSizeMethod

java.lang.Object
org.datanucleus.store.rdbms.sql.method.MapSizeMethod
All Implemented Interfaces:
SQLMethod

public class MapSizeMethod extends Object implements SQLMethod
Method for evaluating {mapExpr}.size(). Returns a NumericExpression. Equates to a sub-query on the table for the map returning the COUNT(*) of the number of entries. Something like
 SELECT COUNT(*) FROM MAPTABLE A0_SUB WHERE A0_SUB.OWNER_ID_OID = A0.OWNER_ID
 
where A0 is the candidate table in the outer query, and MAPTABLE is the join table (if using join map) or the key/value table (if using FK map).
  • Constructor Details

    • MapSizeMethod

      public MapSizeMethod()
  • Method Details

    • getExpression

      public SQLExpression getExpression(SQLStatement stmt, SQLExpression expr, List<SQLExpression> args)
      Description copied from interface: SQLMethod
      Return the expression for this SQL function.
      Specified by:
      getExpression in interface SQLMethod
      Parameters:
      stmt - SQLStatement that this expression is for
      expr - The expression that it is invoked on
      args - Arguments passed in
      Returns:
      The SQL expression using the SQL function