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javatools.db
Class DbUpdater  

java.lang.Object
  javatools.db.DbUpdater

Direct Known Subclasses:

DbReferencedUpdater

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public class DbUpdater

extends java.lang.Object

A class used to update records from SQL tables. The constructor is not public. To obtain a DbUpdater call DbTable.updater(); Example: To update all the people who are (younger than 18 or older than 80) and whose name is "Fred"... to have a favourite_team of "Raiders";

 DbDatabase db = ...;
 DbTable people = db.getTable("PEOPLE");
 DbUpdater updater = people.deleter();
 updater.addColumn(people.getColumn("FAVOURITE_TEAM"), "Raiders");
 updater.setWhere(people.getColumn("AGE").lessThan(new Integer(18)).or(
  people.getColumn("AGE").greaterThan(new Integer(80))).and(
  people.getColumn("NAME").equal("FRED"));
 int numberOfPeopleUpdated = updater.execute();
 

This is equivilent to...

 UPDATE PEOPLE SET FAVOURITE_TEAM='Raiders' WHERE (AGE < 18 OR AGE > 80 ) AND NAME='Fred'
 

Note the use of equal(), NOT equals(). To get more fancy, to update the same group of people to have a favourite team the same as Bill's team, we use a sub-select...

 DbDatabase db = ...;
 DbTable people = db.getTable("PEOPLE");
 DbSelector bills_team = db.selector();
 bills_team.addColumn(people.getColumn("FAVOURITE_TEAM"));
 bills_team.setWhere(people.getColumn("NAME").equal("BILL"));
 DbUpdater updater = people.deleter();
 updater.addColumn(people.getColumn("FAVOURITE_TEAM"), bills_team);
 updater.setWhere(people.getColumn("AGE").lessThan(new Integer(18)).or(
  people.getColumn("AGE").greaterThan(new Integer(80))).and(
  people.getColumn("NAME").equal("FRED"));
 int numberOfPeopleUpdated = updater.execute();
 

This is equivilent to...

 UPDATE PEOPLE SET FAVOURITE_TEAM=(SELECT FAVOURITE_TEAM FROM PEOPLE WHERE NAME='Bill')
  WHERE (AGE < 18 OR AGE > 80 ) AND NAME='Fred'
 

Version:

0.2.0

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Field Summary
(package private)  java.util.List	fromList           The list of data to update.
(package private)  java.util.List	intoList           The list of columns to update.
(package private)  DbAbstractTable	table           The table to update.
(package private)  DbExpr	where           The where condition, specifying which rows will be affected.

 

Constructor Summary
(package private)	DbUpdater(DbAbstractTable table)           Creates a new DbUpdater.

 

Method Summary
void	addColumn(DbColumn into, java.lang.Object from)           Add a column specification to update.
int	execute()           Execute this command on the default connection.
int	execute(DbConnection dbcon)           Execute this delete command on a specific connection.
(package private)  java.lang.String	getQueryString()           Returns the query string for this object.
void	setLists(java.util.List pIntoList, java.util.List pFromList)           Sets in one time the column list and the value list.
(package private)  int	setSqlValues(java.sql.PreparedStatement stmt, int i)           Sets values for the statement.
void	setWhere(DbExpr where)           Set the where condition on which records to update.

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

table

DbAbstractTable table

The table to update.

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intoList

java.util.List intoList

The list of columns to update.

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fromList

java.util.List fromList

The list of data to update.

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where

DbExpr where

The where condition, specifying which rows will be affected.

Constructor Detail

DbUpdater

DbUpdater(DbAbstractTable table)

Creates a new DbUpdater.

Method Detail

setWhere

public void setWhere(DbExpr where)

Set the where condition on which records to update.

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addColumn

public void addColumn(DbColumn into,
                      java.lang.Object from)

Add a column specification to update. The new value can either be a raw value - Integer, String, java.sql.Date etc. Or it can be a DbSelector in the case of a sub-select.

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setLists

public void setLists(java.util.List pIntoList,
                     java.util.List pFromList)

Sets in one time the column list and the value list.

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execute

public int execute(DbConnection dbcon)
            throws DbException

Execute this delete command on a specific connection.

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execute

public int execute()
            throws DbException

Execute this command on the default connection.

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setSqlValues

int setSqlValues(java.sql.PreparedStatement stmt,
                 int i)
           throws DbException,
                  java.sql.SQLException

Sets values for the statement.

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getQueryString

java.lang.String getQueryString()
                          throws DbException

Returns the query string for this object.

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