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java.lang.Objectorg.apache.derby.impl.sql.compile.QueryTreeNode
org.apache.derby.impl.sql.compile.ValueNode
org.apache.derby.impl.sql.compile.BaseColumnNode
public class BaseColumnNode
A BaseColumnNode represents a column in a base table. The parser generates a BaseColumnNode for each column reference. A column refercence could be a column in a base table, a column in a view (which could expand into a complex expression), or a column in a subquery in the FROM clause. By the time we get to code generation, all BaseColumnNodes should stand only for columns in base tables.
Field Summary | |
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private java.lang.String |
columnName
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private TableName |
tableName
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Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode |
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transformed |
Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode |
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AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, isPrivilegeCollectionRequired |
Constructor Summary | |
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BaseColumnNode()
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Method Summary | |
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void |
generateExpression(ExpressionClassBuilder acb,
MethodBuilder mb)
Do the code generation for this node. |
java.lang.String |
getColumnName()
Get the name of this column |
protected int |
getOrderableVariantType()
Return the variant type for the underlying expression. |
java.lang.String |
getSchemaName()
Get the user-supplied schema name for this column's table. |
java.lang.String |
getTableName()
Get the user-supplied table name of this column. |
void |
init(java.lang.Object columnName,
java.lang.Object tableName,
java.lang.Object dts)
Initializer for when you only have the column name. |
protected boolean |
isEquivalent(ValueNode o)
Tests if this node is equivalent to the specified ValueNode. |
java.lang.String |
toString()
Convert this object to a String. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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private java.lang.String columnName
private TableName tableName
Constructor Detail |
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public BaseColumnNode()
Method Detail |
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public void init(java.lang.Object columnName, java.lang.Object tableName, java.lang.Object dts) throws StandardException
init
in class QueryTreeNode
columnName
- The name of the column being referencedtableName
- The qualification for the columndts
- DataTypeServices for the column
StandardException
- Thrown on errorpublic java.lang.String toString()
toString
in class ValueNode
public java.lang.String getColumnName()
getColumnName
in class ValueNode
public java.lang.String getTableName()
getTableName
in class ValueNode
public java.lang.String getSchemaName() throws StandardException
getSchemaName
in class ValueNode
StandardException
public void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
generateExpression
in class ValueNode
acb
- The ExpressionClassBuilder for the class being builtmb
- The method the code to place the code
StandardException
- Thrown on errorprotected int getOrderableVariantType()
getOrderableVariantType
in class ValueNode
protected boolean isEquivalent(ValueNode o)
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:
isEquivalent
in class ValueNode
o
- the node to compare this ValueNode against.
true
if the two nodes are equivalent,
false
otherwise.
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Built on Thu 2012-03-29 21:53:33+0000, from revision ??? | ||||||||
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