Class Statement

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected StatementTree cmd
      The StatementTree object that is the container for the query.
      protected DatabaseConnection database
      The Database context.
      protected SQLQuery query
      The SQLQuery object that was used to produce this statement.
      protected java.util.Vector table_list
      The list of all FromTableInterface objects of resources referenced in this query.
      protected User user
      The user context.
    • Constructor Summary

      Constructors 
      Constructor Description
      Statement()  
    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      protected void addTable​(FromTableInterface table)
      Add an FromTableInterface that is used within this query.
      DebugLogger Debug()
      Returns a DebugLogger object used to log debug commands.
      abstract Table evaluate()
      Evaluates the statement and returns a table that represents the result set.
      void init​(DatabaseConnection db, StatementTree stree, SQLQuery query)
      Sets up internal variables for this statement for derived classes to use.
      abstract void prepare()
      Prepares the statement with the given Database object.
      void resolveTree()
      Performs initial preparation on the contents of the StatementTree by resolving all sub queries and mapping functions to their executable forms.
      Variable resolveVariableName​(Variable v)
      Given a Variable object, this will resolve the name into a column name the database understands (substitutes aliases, etc).
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • user

        protected User user
        The user context.
      • cmd

        protected StatementTree cmd
        The StatementTree object that is the container for the query.
      • query

        protected SQLQuery query
        The SQLQuery object that was used to produce this statement.
      • table_list

        protected java.util.Vector table_list
        The list of all FromTableInterface objects of resources referenced in this query. (FromTableInterface)
    • Constructor Detail

      • Statement

        public Statement()
    • Method Detail

      • Debug

        public final DebugLogger Debug()
        Returns a DebugLogger object used to log debug commands.
      • resolveTree

        public final void resolveTree()
                               throws DatabaseException
        Performs initial preparation on the contents of the StatementTree by resolving all sub queries and mapping functions to their executable forms.

        Given a StatementTree and a Database context, this method will convert all sub-queries found in the StatementTree to a Queriable object. In other words, all StatementTree are converted to Select objects. The given 'database' object is used as the session to prepare the sub-queries against.

        This is called after 'init' and before 'prepare'.

        Throws:
        DatabaseException
      • resolveVariableName

        public Variable resolveVariableName​(Variable v)
        Given a Variable object, this will resolve the name into a column name the database understands (substitutes aliases, etc).
      • addTable

        protected void addTable​(FromTableInterface table)
        Add an FromTableInterface that is used within this query. These tables are used when we try to resolve a column name.
      • init

        public final void init​(DatabaseConnection db,
                               StatementTree stree,
                               SQLQuery query)
        Sets up internal variables for this statement for derived classes to use. This is called before 'prepare' and 'isExclusive' is called.

        It is assumed that any ? style parameters in the StatementTree will have been resolved previous to a call to this method.

        Parameters:
        db - the DatabaseConnection that will execute this statement.
        stree - the StatementTree that contains the parsed content of the statement being executed.
      • prepare

        public abstract void prepare()
                              throws DatabaseException
        Prepares the statement with the given Database object. This is called before the statement is evaluated. The prepare statement queries the database and resolves information about the statement (for example, it resolves column names and aliases and determines the tables that are touched by this statement so we can lock the appropriate tables before we evaluate).

        NOTE: Care must be taken to ensure that all methods called here are safe in as far as modifications to the data occuring. The rules for safety should be as follows. If the database is in EXCLUSIVE mode, then we need to wait until it's switched back to SHARED mode before this method is called. All collection of information done here should not involve any table state info. except for column count, column names, column types, etc. Queries such as obtaining the row count, selectable scheme information, and certainly 'getCellContents' must never be called during prepare. When prepare finishes, the affected tables are locked and the query is safe to 'evaluate' at which time table state is safe to inspect.

        Throws:
        DatabaseException