Package com.mckoi.database
Class SubsetColumnTable
- java.lang.Object
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- com.mckoi.database.Table
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- com.mckoi.database.FilterTable
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- com.mckoi.database.SubsetColumnTable
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- All Implemented Interfaces:
RootTable
,TableDataSource
public final class SubsetColumnTable extends FilterTable implements RootTable
This object is a filter that sits atop a Table object. Its purpose is to only provide a view of the columns that are required. In a Select query we may create a query with only the subset of columns that were originally in the table set. This object allows us to provide an interface to only the columns that the Table is allowed to access.This method implements RootTable which means a union operation will not decend further past this table when searching for the roots.
- Author:
- Tobias Downer
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Field Summary
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Fields inherited from class com.mckoi.database.FilterTable
parent
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Fields inherited from class com.mckoi.database.Table
DEBUG_QUERY
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Constructor Summary
Constructors Constructor Description SubsetColumnTable(Table parent)
The Constructor.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
findFieldName(Variable v)
Given a fully qualified variable field name, ie.TObject
getCellContents(int column, int row)
Returns an object that represents the information in the given cell in the table.int
getColumnCount()
Returns the number of columns in the table.DataTableDef
getDataTableDef()
Returns the DataTableDef object that describes the columns and name of this table.Variable
getResolvedVariable(int column)
Returns a fully qualified Variable object that represents the name of the column at the given index.void
setColumnMap(int[] mapping, Variable[] aliases)
Adds a column map into this table.java.lang.String
toString()
Returns a string that represents this table.boolean
typeEquals(RootTable table)
This function is used to check that two tables are identical.-
Methods inherited from class com.mckoi.database.FilterTable
getDatabase, getParent, getRowCount, hasRootsLocked, lockRoot, printGraph, rowEnumeration, unlockRoot
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Methods inherited from class com.mckoi.database.Table
all, allColumnMatchesValue, any, columnContainsCell, columnContainsValue, columnMatchesValue, columnMerge, compareCells, Debug, distinct, distinct, dumpTo, emptySelect, exhaustiveSelect, fastFindFieldName, getColumnDefAt, getColumnScheme, getFirstCellContent, getFirstCellContent, getLastCellContent, getLastCellContent, getSingleCellContent, getSingleCellContent, getSystem, getTableAccessState, getTTypeForColumn, getTTypeForColumn, join, orderByColumn, orderByColumn, orderByColumn, orderByColumns, orderedRowList, outside, rangeSelect, selectAll, selectAll, selectFirst, selectLast, selectRange, selectRest, simpleJoin, simpleSelect, singleRowSelect, toMap, union
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Constructor Detail
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SubsetColumnTable
public SubsetColumnTable(Table parent)
The Constructor.
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Method Detail
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setColumnMap
public void setColumnMap(int[] mapping, Variable[] aliases)
Adds a column map into this table. The int array contains a map to the column in the parent object that we want the column number to reference. For example, to select columns 4, 8, 1, 2 into this new table, the array would be { 4, 8, 1, 2 }.
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getColumnCount
public int getColumnCount()
Returns the number of columns in the table.- Overrides:
getColumnCount
in classFilterTable
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findFieldName
public int findFieldName(Variable v)
Given a fully qualified variable field name, ie. 'APP.CUSTOMER.CUSTOMERID' this will return the column number the field is at. Returns -1 if the field does not exist in the table.- Overrides:
findFieldName
in classFilterTable
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getDataTableDef
public DataTableDef getDataTableDef()
Returns the DataTableDef object that describes the columns and name of this table. For a SubsetColumnTable object, this returns the columns that were mapped via the 'setColumnMap' method.- Specified by:
getDataTableDef
in interfaceTableDataSource
- Overrides:
getDataTableDef
in classFilterTable
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getResolvedVariable
public Variable getResolvedVariable(int column)
Returns a fully qualified Variable object that represents the name of the column at the given index. For example, new Variable(new TableName("APP", "CUSTOMER"), "ID")- Overrides:
getResolvedVariable
in classFilterTable
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getCellContents
public final TObject getCellContents(int column, int row)
Returns an object that represents the information in the given cell in the table. This will generally be an expensive algorithm, so calls to it should be kept to a minimum. Note that the offset between two rows is not necessarily 1.- Specified by:
getCellContents
in interfaceTableDataSource
- Overrides:
getCellContents
in classFilterTable
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typeEquals
public boolean typeEquals(RootTable table)
This function is used to check that two tables are identical. This is used in operations like 'union' that need to determine that the roots are infact of the same type.- Specified by:
typeEquals
in interfaceRootTable
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