## org.springframework.jdbc.support.incrementer
Class MySQLMaxValueIncrementer

    java.lang.Object
      org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
          org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer
              org.springframework.jdbc.support.incrementer.MySQLMaxValueIncrementer

All Implemented Interfaces:
  InitializingBean, DataFieldMaxValueIncrementer

    public class MySQLMaxValueIncrementer

extends AbstractColumnMaxValueIncrementer

`DataFieldMaxValueIncrementer` that increments the maximum value of a given MySQL table with the equivalent of an auto-increment column. Note: If you use this class, your MySQL key column should NOT be auto-increment, as the sequence table does the job.

The sequence is kept in a table; there should be one sequence table per table that needs an auto-generated key. The table type of the sequence table should be MyISAM so the sequences are allocated without regard to any transactions that might be in progress.

Example:

    create table tab (id int unsigned not null primary key, text varchar(100));
     create table tab_sequence (value int not null) type=MYISAM;
     insert into tab_sequence values(0);

If "cacheSize" is set, the intermediate values are served without querying the database. If the server or your application is stopped or crashes or a transaction is rolled back, the unused values will never be served. The maximum hole size in numbering is consequently the value of cacheSize.

Author:
  Jean-Pierre Pawlak, Thomas Risberg, Juergen Hoeller

Field Summary

Fields inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
`paddingLength`

Constructor Summary
`MySQLMaxValueIncrementer()` Default constructor for bean property style usage.
`MySQLMaxValueIncrementer(DataSource dataSource, String incrementerName, String columnName)` Convenience constructor.

Method Summary
`protected long` `getNextKey()` Determine the next key to use, as a long.

Methods inherited from class org.springframework.jdbc.support.incrementer.AbstractColumnMaxValueIncrementer
`afterPropertiesSet, getCacheSize, getColumnName, setCacheSize, setColumnName`

Methods inherited from class org.springframework.jdbc.support.incrementer.AbstractDataFieldMaxValueIncrementer
`getDataSource, getIncrementerName, getPaddingLength, nextIntValue, nextLongValue, nextStringValue, setDataSource, setIncrementerName, setPaddingLength`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### MySQLMaxValueIncrementer

    public MySQLMaxValueIncrementer()

  Default constructor for bean property style usage.

  See Also:
    `AbstractDataFieldMaxValueIncrementer.setDataSource(javax.sql.DataSource)`, `AbstractDataFieldMaxValueIncrementer.setIncrementerName(java.lang.String)`, `AbstractColumnMaxValueIncrementer.setColumnName(java.lang.String)`

### MySQLMaxValueIncrementer

    public MySQLMaxValueIncrementer(DataSource dataSource,
                                    String incrementerName,
                                    String columnName)

  Convenience constructor.

  Parameters:
    `dataSource` - the DataSource to use
    `incrementerName` - the name of the sequence/table to use
    `columnName` - the name of the column in the sequence table to use

Method Detail

### getNextKey

    protected long getNextKey()
                       throws DataAccessException

  Description copied from class: `AbstractDataFieldMaxValueIncrementer`
  Determine the next key to use, as a long.

  Specified by:
    `getNextKey` in class `AbstractDataFieldMaxValueIncrementer`
  Returns:
    the key to use as a long. It will eventually be converted later in another format by the public concrete methods of this class.
  Throws:
    `DataAccessException`

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