Package uk.ac.starlink.table.jdbc
Class JDBCStarTable
- java.lang.Object
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- uk.ac.starlink.table.AbstractStarTable
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- uk.ac.starlink.table.jdbc.JDBCStarTable
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- All Implemented Interfaces:
StarTable
public class JDBCStarTable extends AbstractStarTable
A StarTable implementation based on the results of an SQL query on a JDBC table.
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Constructor Summary
Constructors Constructor Description JDBCStarTable(Connector connx, java.lang.String sql)
Constructs a StarTable representing the data returned by an SQL query using a JDBC connections from a given source, with sequential access only.JDBCStarTable(Connector connx, java.lang.String sql, boolean isRandom)
Constructs a StarTable representing the data returned by an SQL query using JDBC connections from a given source, optionally providing random access.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
getCell(long lrow, int icol)
The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.java.util.List
getColumnAuxDataInfos()
Goes through the table columns (ColumnInfo objects) and picks out all the AuxData items which exist, generalising where necessary and returning a union of them in alphabetical order by name.int
getColumnCount()
Returns the number of columns in this table.ColumnInfo
getColumnInfo(int icol)
Returns the object describing the data in a given column.java.sql.Connection
getConnection()
Returns a JDBC Connection that can supply the data for this table.java.lang.Object[]
getRow(long lrow)
The AbstractStarTable implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.long
getRowCount()
Returns the number of rows in this table, if known.RowSequence
getRowSequence()
Returns an object which can iterate over all the rows in the table sequentially.java.lang.String
getSql()
Returns the text of the SQL query used for this table.boolean
isRandom()
The AbstractStarTable implementation of this method returns false.void
setRandom()
Ensures that this table provides random access.-
Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, getName, getParameterByName, getParameters, getURL, setName, setParameter, setParameters, setURL
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Constructor Detail
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JDBCStarTable
public JDBCStarTable(Connector connx, java.lang.String sql) throws java.sql.SQLException
Constructs a StarTable representing the data returned by an SQL query using a JDBC connections from a given source, with sequential access only.- Parameters:
connx
- object which can supply JDBC connectionssql
- text of the SQL query- Throws:
java.sql.SQLException
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JDBCStarTable
public JDBCStarTable(Connector connx, java.lang.String sql, boolean isRandom) throws java.sql.SQLException
Constructs a StarTable representing the data returned by an SQL query using JDBC connections from a given source, optionally providing random access.This was initially written to take a
Connection
rather than aConnector
object, but it seems that there are limits to the number of ResultSets that can be simultaneously open on a Connection.- Parameters:
connx
- object which can supply JDBC connectionssql
- text of the SQL queryisRandom
- whether this table needs to provide random access or not (there are costs associated with this)- Throws:
java.sql.SQLException
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Method Detail
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getColumnInfo
public ColumnInfo getColumnInfo(int icol)
Description copied from interface:StarTable
Returns the object describing the data in a given column.- Specified by:
getColumnInfo
in interfaceStarTable
- Specified by:
getColumnInfo
in classAbstractStarTable
- Parameters:
icol
- the column for which header information is required- Returns:
- a ValueInfo object for column icol
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getColumnAuxDataInfos
public java.util.List getColumnAuxDataInfos()
Description copied from class:AbstractStarTable
Goes through the table columns (ColumnInfo objects) and picks out all the AuxData items which exist, generalising where necessary and returning a union of them in alphabetical order by name. Subclasses should override this if they can do better, for instance providing an order for the keys.- Specified by:
getColumnAuxDataInfos
in interfaceStarTable
- Overrides:
getColumnAuxDataInfos
in classAbstractStarTable
- Returns:
- a list of all the auxiliary metadata ValueInfo items which in fact crop up in column metadata
- See Also:
ColumnInfo.getAuxData()
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getColumnCount
public int getColumnCount()
Description copied from interface:StarTable
Returns the number of columns in this table.- Specified by:
getColumnCount
in interfaceStarTable
- Specified by:
getColumnCount
in classAbstractStarTable
- Returns:
- the number of columns
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getRowCount
public long getRowCount()
Description copied from interface:StarTable
Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.- Specified by:
getRowCount
in interfaceStarTable
- Specified by:
getRowCount
in classAbstractStarTable
- Returns:
- the number of rows, or -1
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setRandom
public void setRandom() throws java.sql.SQLException
Ensures that this table provides random access. Following this call the isRandom method will return true. Calling this method multiple times is harmless.- Throws:
java.sql.SQLException
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isRandom
public boolean isRandom()
Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method returns false.- Specified by:
isRandom
in interfaceStarTable
- Overrides:
isRandom
in classAbstractStarTable
- Returns:
- true if table random access methods are available
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getCell
public java.lang.Object getCell(long lrow, int icol) throws java.io.IOException
Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method throws an UnsupportedOperationException, since unless otherwise provided there is no random access.- Specified by:
getCell
in interfaceStarTable
- Overrides:
getCell
in classAbstractStarTable
- Parameters:
lrow
- the index of the cell's rowicol
- the index of the cell's column- Returns:
- the contents of this cell
- Throws:
java.io.IOException
- if there is an error reading the data
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getRow
public java.lang.Object[] getRow(long lrow) throws java.io.IOException
Description copied from class:AbstractStarTable
The AbstractStarTable implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.- Specified by:
getRow
in interfaceStarTable
- Overrides:
getRow
in classAbstractStarTable
- Parameters:
lrow
- the index of the row to retrieve- Returns:
- an array of the objects in each cell in row irow
- Throws:
java.io.IOException
- if there is an error reading the data
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getRowSequence
public RowSequence getRowSequence() throws java.io.IOException
Description copied from interface:StarTable
Returns an object which can iterate over all the rows in the table sequentially.- Specified by:
getRowSequence
in interfaceStarTable
- Specified by:
getRowSequence
in classAbstractStarTable
- Returns:
- an object providing sequential access to the table data
- Throws:
java.io.IOException
- if there is an error providing access
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getConnection
public java.sql.Connection getConnection() throws java.sql.SQLException
Returns a JDBC Connection that can supply the data for this table.- Returns:
- a JDBC Connection object
- Throws:
java.sql.SQLException
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getSql
public java.lang.String getSql()
Returns the text of the SQL query used for this table.- Returns:
- the SQL query text
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