Field Detail

• columnName

  private java.lang.String columnName

• tableName

  private TableName tableName

Constructor Detail

• BaseColumnNode

  BaseColumnNode​(java.lang.String columnName,
                 TableName tableName,
                 DataTypeDescriptor dtd,
                 ContextManager cm)
          throws StandardException

  Constructor for a referenced column name

  Parameters:

  columnName - The name of the column being referenced

  tableName - The qualification for the column

  dtd - Data type descriptor for the column

  cm - Context manager

  Throws:

  StandardException

Method Detail

• toString

  public java.lang.String toString()

  Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

  Overrides:

  toString in class ValueNode

  Returns:

  This object as a String

• getColumnName

  java.lang.String getColumnName()

  Get the name of this column

  Overrides:

  getColumnName in class ValueNode

  Returns:

  The name of this column

• getTableName

  java.lang.String getTableName()

  Get the user-supplied table name of this column. This will be null if the user did not supply a name (for example, select a from t). The method will return B for this example, select b.a from t as b The method will return T for this example, select t.a from t

  Overrides:

  getTableName in class ValueNode

  Returns:

  The user-supplied name of this column. Null if no user- supplied name.

• getSchemaName

  java.lang.String getSchemaName()
                          throws StandardException

  Get the user-supplied schema name for this column's table. This will be null if the user did not supply a name (for example, select t.a from t). Another example for null return value (for example, select b.a from t as b). But for following query select app.t.a from t, this will return APP

  Overrides:

  getSchemaName in class ValueNode

  Returns:

  The schema name for this column's table

  Throws:

  StandardException

• generateExpression

  void generateExpression​(ExpressionClassBuilder acb,
                          MethodBuilder mb)
                   throws StandardException

  Do the code generation for this node. Should never be called.

  Overrides:

  generateExpression in class ValueNode

  Parameters:

  acb - The ExpressionClassBuilder for the class being built

  mb - The method the code to place the code

  Throws:

  StandardException - Thrown on error

• getOrderableVariantType

  protected int getOrderableVariantType()

  Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)

  Overrides:

  getOrderableVariantType in class ValueNode

  Returns:

  The variant type for the underlying expression.

• isEquivalent

  boolean isEquivalent​(ValueNode o)

  Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

  This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

  Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

  One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

  SELECT c1+c2 FROM t1 GROUP BY c1+c2

  In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

  • The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
  • If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
  • If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
  • When comparing SQL NULLs in this context, they are considered to be equivalent.
  • If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.

  Specified by:

  isEquivalent in class ValueNode

  Parameters:

  o - the node to compare this ValueNode against.

  Returns:

  true if the two nodes are equivalent, false otherwise.

• acceptChildren

  void acceptChildren​(Visitor v)
               throws StandardException

  Description copied from class: QueryTreeNode
  Accept a visitor on all child nodes. All sub-classes that add fields that should be visited, should override this method and call accept(v) on all visitable fields, as well as super.acceptChildren(v) to make sure all visitable fields defined by the super-class are accepted too.

  Overrides:

  acceptChildren in class QueryTreeNode

  Parameters:

  v - the visitor

  Throws:

  StandardException - on errors raised by the visitor