StmtAlterColumn.java :  » Database-DBMS » Quadcap-Embeddable-Database » com » quadcap » sql » Java Open Source

package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
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import java.io.IOException;

import java.sql.SQLException;

/**
 * Implementation of SQL <b>ALTER COLUMN</b> statement.
 *
 * @author Stan Bailes
 */
public class StmtAlterColumn implements Stmt {
    String        tableName;
    String        columnName;
    Expression        defaultVal;

    public StmtAlterColumn(String tableName, String columnName,
         Expression defaultVal) { 
  this.tableName = tableName;
  this.columnName = columnName;
  this.defaultVal = defaultVal;
    }

    public void execute(Session session) throws IOException, SQLException {
  session.getTableWriteLock("#Schema");
  session.getTableWriteLock(tableName);
  Database db = session.getDatabase();
  Table table = (Table)db.getRelation(tableName);
        if (table == null) {
            throw new SQLException("Table not found: " + tableName);
        }
  session.doStep(new AlterColumn(session, table, columnName, defaultVal));
    }
}