aglappe-0.6/tools/MySQLConnection.java

package tools;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.StringTokenizer;
import java.io.IOException;
import java.util.ArrayList;

public class MySQLConnection {

        /*--------------------- constants -----------------------*/
        
    // -- constants for database connection --
    static final String    HOST =                       "white";        
    static final String    USER =                   "";
    static final String    PASSWORD =           "nieve";
        
        /*------------------- member variables --------------------*/
        
        public Connection conn; 
        private String host;
        private String user;
        private String password=PASSWORD;
        private String port;
        private String dbname;
        
        /*-------------------- constructors -----------------------*/

        /**
         * Connect to database using the given server, user and password
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword) {
                loadMySQLDriver();
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port="";
                dbname="";              
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;
                try {
                        conn = DriverManager.getConnection(connStr, user, password);
                } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
                } // end try/catch connection                            
        }

        /**
         * Connect to database using the given server, user, password and dbname
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName) {
                loadMySQLDriver();
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port="";
                dbname=dbName;          
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;
                try {
                        conn = DriverManager.getConnection(connStr, user, password);
                } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
                } // end try/catch connection                            
        }

        /**
         * Connect to database using the given server, user, password, dbname and port
         */
        public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName, int portNum) {
                loadMySQLDriver();
                host=dbServer;
                user=dbUserName;
                password=dbPassword;
                port=":"+portNum;
                dbname=dbName;          
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;
                try {
                        conn = DriverManager.getConnection(connStr, user, password);
                } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
                } // end try/catch connection                            
        }
                
        /**
         * Connect to database giving a connection file 
         */
        public MySQLConnection(String connFile) {               
                loadMySQLDriver();
                readConnectionFile(connFile);
                String connStr="jdbc:mysql://"+host+port+"/"+dbname;
                try {
                        conn = DriverManager.getConnection(connStr, user, password);
                } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
                } // end try/catch connection                            
        }
        
        
        /*---------------------- methods -------------------------*/
        
        private void loadMySQLDriver() {
                try {
                        Class.forName("com.mysql.jdbc.Driver").newInstance();
                }
                catch(Exception e) {
                        e.printStackTrace();
                        System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
                        System.exit(1);
                }
        }

        public Statement createStatement() throws SQLException {
                return this.conn.createStatement();
        }
        
        public void executeSql(String query) throws SQLException{
                Statement stmt;         
                stmt = conn.createStatement();  
                stmt.execute(query);
                stmt.close();               
        }
        
        /** 
         * @param query
         * @return the first column of the first row of the result of the given query as a string
         * or null if no results were returned
         */     
        public String getStringFromDb(String query) {
                Statement    stmt;
                ResultSet    rs;
                String       result = null;
                
                try { 
                        
                    stmt = conn.createStatement();
                    rs = stmt.executeQuery(query);
                    if(rs.next()) {
                        result = rs.getString(1);
                    }
                    rs.close();
                    stmt.close(); 
                    
                } // end try
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end catch                          
                
                return result;
        }
        
        /** 
         * @param query
         * @return the first column of the first row of the result of the given query as an integer
         * or -1 if no results were returned
         */
        public int getIntFromDb(String query) {
                Statement    stmt;
                ResultSet    rs;
                int          result = -1;

                try { 
                        
                    stmt = conn.createStatement();
                    rs = stmt.executeQuery(query);
                    if(rs.next()) {
                        result = rs.getInt(1);
                    }
                    rs.close();
                    stmt.close(); 
                    
                } // end try
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end catch                  
                
                return result;
        }
        
        public void close() {
                
                try {
                        conn.close();
            } catch (SQLException e) {
                        System.err.println("SQLException: " + e.getMessage());
                        System.err.println("SQLState:     " + e.getSQLState());
                        System.err.println("VendorError:  " + e.getErrorCode());
                        e.printStackTrace();
            } // end try/catch connection 
        }
        
        /**
         * Get the actual Connection object within this MySQLConnection. In case that an external library need a Connection object
         * @return
         */
        public Connection getConnectionObject() {
                return this.conn;
        }

        /**
         * Used in the constructor that gets a connFile as argument. To read the connection parameters from a connection file.
         * @param connFile
         */
        private void readConnectionFile(String connFile) {
                // reads the values of the connFile into the static variables; 
                String homedir = System.getProperty("user.home"); 
                if (connFile.length()==0) { // no file was specified
                        connFile=homedir+"/.my.cnf"; // assume default configuration file 
                }               
                // else the location of the connection file was given           
                // Open the configuration file          
                BufferedReader fileIn = null;
                StringTokenizer str;
                String item, oneLine;
                // to control if the minimum necessary 3 parameters are given in file
                int cfgParsPresent=0; 
                // setting default blank values for port and dbname, they are set to blank unless fields specified in file
                port="";
                dbname="";
                // list the entries in the file and decompose them 
                try {
                        fileIn = new BufferedReader(new FileReader(new File(connFile))); // open BufferedReader to file connFile 
                        while ((oneLine = fileIn.readLine()) != null ) {
                                // Construct a stringTokenizer for the line that we read with : delimited
                                str = new StringTokenizer(oneLine, "="); // true sets returnDelimiters flag 
                                while ( str.hasMoreTokens()) {
                                        item = str.nextToken();
                                        if( item.equals("host")) { // mandatory parameter
                                                host=str.nextToken();
                                                cfgParsPresent++;
                                                break; 
                                        } // end if host 
                                        if( item.equals("port")) { // optional parameter
                                                port=":"+str.nextToken();
                                                break; 
                                        } // end if port
                                        if( item.equals("user")) { // mandatory parameter
                                                user=str.nextToken();
                                                cfgParsPresent++;
                                                break; 
                                        } // end if password 
                                        if( item.equals("password")) { // mandatory parameter
                                                password=str.nextToken();
                                                cfgParsPresent++;
                                                break; 
                                        } // end if password
                                        if( item.equals("database")) { // optional parameter
                                                dbname=str.nextToken();
                                                break; 
                                        } // end if password                                    
                                } // next token in this line 
                        } // next line in the file
                        if (cfgParsPresent<3){
                                System.err.println("Not all mandatory parameters are given in connection file "+connFile+". Can't connect to mysql server, exiting.");
                                System.exit(1);
                        }                       
                } 
                catch (IOException e) {
                        System.err.println("Couldn't open file "+connFile);                     
                        e.printStackTrace();
                        System.exit(1);
                }  
                
                try { // closing the file
                        if (fileIn != null) fileIn.close();                     
                } catch (IOException e) {
                        System.err.println("Couldn't close file "+connFile);
                        e.printStackTrace(); 
                }
                
        }

    /**
     * To print the db size info for the given db of this MySQLConnection.
     * @param dbName
     */
        public void printDbSizeInfo (String dbName) {
                double data = 0, index = 0, table_data = 0, table_index = 0, GB = Math.pow(2, 30);
                String Query = null, table = null;
                Statement Stmt = null;
                ResultSet RS = null;            
                try {
                    Query = "SHOW TABLE STATUS FROM "+dbName;
                    Stmt = this.conn.createStatement();
                    RS = Stmt.executeQuery(Query);
                    while (RS.next()) {
                                table = RS.getString("Name");
                                table_data = RS.getDouble("Data_length");
                                table_index = RS.getDouble("Index_length");
                                data += RS.getDouble("Data_length");
                                index += RS.getDouble("Index_length");
                                System.out.println("Table "+table+"##data:"+table_data+", index:"+table_index);
                    }
                    RS.close();
                    Stmt.close();       
                    System.out.println("Database "+dbName+" needs "+((data+index)/GB)+ " GB (data:"+(data/GB)+", index:"+(index/GB)+").");
                } 
                catch (SQLException e) {
                    System.err.println("SQLException: " + e.getMessage());
                    System.err.println("SQLState:     " + e.getSQLState());
                    System.err.println("VendorError:  " + e.getErrorCode());
                    e.printStackTrace();
                } // end try/catch connection
    }

    /**
     * To get range of a column from a table in this MySQLConnection. Note that if the connection was created without pointing 
     * to a particular database then the argument table must be specified as dbname.tablename.
     * @param table
     * @param column
     * @return
     */
    public double[] getRange(String table, String column) {
        String query = "";
        Statement S;
        ResultSet R;
        double[] range = new double[2];
        try { 
            query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+";";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            if (R.next()) {
                        range[0] = R.getDouble(1);
                        range[1] = R.getDouble(2);
            } 
            R.close();
            S.close();
        } // end try
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch          
        return range;           
    }

    /**
     * To get range of a column from a table in this MySQLConnection using a given WHERE condition. Note that if 
     * the connection was created without pointing to a particular database then the argument table must 
     * be specified as dbname.tablename.
     * @param table
     * @param column
     * @param whereStr
     * @return
     */
    public double[] getRange(String table, String column, String whereStr) {
        String query = "";
        Statement S;
        ResultSet R;
        double[] range = new double[2];
        try { 
            query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+" WHERE ("+whereStr+");";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            if (R.next()) {
                        range[0] = R.getDouble(1);
                        range[1] = R.getDouble(2);
            } 
            R.close();
            S.close();
        } // end try
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch          
        return range;           
    }
        
    /**
     * To get all indexes for a certain table. Note the MySQLConnection object must be created with a non-blank database.
     * @param table
     * @return
     */
    public String[] getAllIndexes4Table(String table) {
        ArrayList<String> indexesAL=new ArrayList<String>();
        String query;
        Statement S;
        ResultSet R;
        try { 
            query = "SELECT index_name from INFORMATION_SCHEMA.statistics WHERE table_schema='"+dbname+"' AND table_name='"+table+"';";
            S = this.conn.createStatement();
            R = S.executeQuery(query);          
            while (R.next()) {
                        indexesAL.add(R.getString(1));                  
            } 
            R.close();
            S.close();
        } // end try                    
        catch (SQLException e) {
            System.err.println("SQLException: " + e.getMessage());
            System.err.println("SQLState:     " + e.getSQLState());
            System.err.println("VendorError:  " + e.getErrorCode());
            e.printStackTrace();
        } // end catch
        String[] indexes=new String[indexesAL.size()];
        int i=0;
        for (String index:indexesAL) {
                indexes[i]=index;
                i++;
        }
        return indexes;
    }
}
Revision:	58
Committed:	Wed Apr 5 08:45:23 2006 UTC (18 years, 6 months ago) by duarte
Original Path:	*trunk/tools/MySQLConnection.java*
File size:	13503 byte(s)
Log Message:	Now executeSQL method throws exception instead of catching it. Thought it was better than the calling class deals with these exceptions.
Line	File contents
1	package tools;
2
3	import java.io.BufferedReader;
4	import java.io.File;
5	import java.io.FileReader;
6	import java.sql.Connection;
7	import java.sql.DriverManager;
8	import java.sql.ResultSet;
9	import java.sql.SQLException;
10	import java.sql.Statement;
11	import java.util.StringTokenizer;
12	import java.io.IOException;
13	import java.util.ArrayList;
14
15	public class MySQLConnection {
16
17	/--------------------- constants -----------------------/
18
19	// -- constants for database connection --
20	static final String HOST = "white";
21	static final String USER = "";
22	static final String PASSWORD = "nieve";
23
24	/------------------- member variables --------------------/
25
26	public Connection conn;
27	private String host;
28	private String user;
29	private String password=PASSWORD;
30	private String port;
31	private String dbname;
32
33	/-------------------- constructors -----------------------/
34
35	/**
36	* Connect to database using the given server, user and password
37	*/
38	public MySQLConnection(String dbServer, String dbUserName, String dbPassword) {
39	loadMySQLDriver();
40	host=dbServer;
41	user=dbUserName;
42	password=dbPassword;
43	port="";
44	dbname="";
45	String connStr="jdbc:mysql://"+host+port+"/"+dbname;
46	try {
47	conn = DriverManager.getConnection(connStr, user, password);
48	} catch (SQLException e) {
49	System.err.println("SQLException: " + e.getMessage());
50	System.err.println("SQLState: " + e.getSQLState());
51	System.err.println("VendorError: " + e.getErrorCode());
52	e.printStackTrace();
53	} // end try/catch connection
54	}
55
56	/**
57	* Connect to database using the given server, user, password and dbname
58	*/
59	public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName) {
60	loadMySQLDriver();
61	host=dbServer;
62	user=dbUserName;
63	password=dbPassword;
64	port="";
65	dbname=dbName;
66	String connStr="jdbc:mysql://"+host+port+"/"+dbname;
67	try {
68	conn = DriverManager.getConnection(connStr, user, password);
69	} catch (SQLException e) {
70	System.err.println("SQLException: " + e.getMessage());
71	System.err.println("SQLState: " + e.getSQLState());
72	System.err.println("VendorError: " + e.getErrorCode());
73	e.printStackTrace();
74	} // end try/catch connection
75	}
76
77	/**
78	* Connect to database using the given server, user, password, dbname and port
79	*/
80	public MySQLConnection(String dbServer, String dbUserName, String dbPassword, String dbName, int portNum) {
81	loadMySQLDriver();
82	host=dbServer;
83	user=dbUserName;
84	password=dbPassword;
85	port=":"+portNum;
86	dbname=dbName;
87	String connStr="jdbc:mysql://"+host+port+"/"+dbname;
88	try {
89	conn = DriverManager.getConnection(connStr, user, password);
90	} catch (SQLException e) {
91	System.err.println("SQLException: " + e.getMessage());
92	System.err.println("SQLState: " + e.getSQLState());
93	System.err.println("VendorError: " + e.getErrorCode());
94	e.printStackTrace();
95	} // end try/catch connection
96	}
97
98	/**
99	* Connect to database giving a connection file
100	*/
101	public MySQLConnection(String connFile) {
102	loadMySQLDriver();
103	readConnectionFile(connFile);
104	String connStr="jdbc:mysql://"+host+port+"/"+dbname;
105	try {
106	conn = DriverManager.getConnection(connStr, user, password);
107	} catch (SQLException e) {
108	System.err.println("SQLException: " + e.getMessage());
109	System.err.println("SQLState: " + e.getSQLState());
110	System.err.println("VendorError: " + e.getErrorCode());
111	e.printStackTrace();
112	} // end try/catch connection
113	}
114
115
116	/---------------------- methods -------------------------/
117
118	private void loadMySQLDriver() {
119	try {
120	Class.forName("com.mysql.jdbc.Driver").newInstance();
121	}
122	catch(Exception e) {
123	e.printStackTrace();
124	System.err.println("An exception occurred while loading the mysql jdbc driver, exiting.");
125	System.exit(1);
126	}
127	}
128
129	public Statement createStatement() throws SQLException {
130	return this.conn.createStatement();
131	}
132
133	public void executeSql(String query) throws SQLException{
134	Statement stmt;
135	stmt = conn.createStatement();
136	stmt.execute(query);
137	stmt.close();
138	}
139
140	/**
141	* @param query
142	* @return the first column of the first row of the result of the given query as a string
143	* or null if no results were returned
144	*/
145	public String getStringFromDb(String query) {
146	Statement stmt;
147	ResultSet rs;
148	String result = null;
149
150	try {
151
152	stmt = conn.createStatement();
153	rs = stmt.executeQuery(query);
154	if(rs.next()) {
155	result = rs.getString(1);
156	}
157	rs.close();
158	stmt.close();
159
160	} // end try
161	catch (SQLException e) {
162	System.err.println("SQLException: " + e.getMessage());
163	System.err.println("SQLState: " + e.getSQLState());
164	System.err.println("VendorError: " + e.getErrorCode());
165	e.printStackTrace();
166	} // end catch
167
168	return result;
169	}
170
171	/**
172	* @param query
173	* @return the first column of the first row of the result of the given query as an integer
174	* or -1 if no results were returned
175	*/
176	public int getIntFromDb(String query) {
177	Statement stmt;
178	ResultSet rs;
179	int result = -1;
180
181	try {
182
183	stmt = conn.createStatement();
184	rs = stmt.executeQuery(query);
185	if(rs.next()) {
186	result = rs.getInt(1);
187	}
188	rs.close();
189	stmt.close();
190
191	} // end try
192	catch (SQLException e) {
193	System.err.println("SQLException: " + e.getMessage());
194	System.err.println("SQLState: " + e.getSQLState());
195	System.err.println("VendorError: " + e.getErrorCode());
196	e.printStackTrace();
197	} // end catch
198
199	return result;
200	}
201
202	public void close() {
203
204	try {
205	conn.close();
206	} catch (SQLException e) {
207	System.err.println("SQLException: " + e.getMessage());
208	System.err.println("SQLState: " + e.getSQLState());
209	System.err.println("VendorError: " + e.getErrorCode());
210	e.printStackTrace();
211	} // end try/catch connection
212	}
213
214	/**
215	* Get the actual Connection object within this MySQLConnection. In case that an external library need a Connection object
216	* @return
217	*/
218	public Connection getConnectionObject() {
219	return this.conn;
220	}
221
222	/**
223	* Used in the constructor that gets a connFile as argument. To read the connection parameters from a connection file.
224	* @param connFile
225	*/
226	private void readConnectionFile(String connFile) {
227	// reads the values of the connFile into the static variables;
228	String homedir = System.getProperty("user.home");
229	if (connFile.length()==0) { // no file was specified
230	connFile=homedir+"/.my.cnf"; // assume default configuration file
231	}
232	// else the location of the connection file was given
233	// Open the configuration file
234	BufferedReader fileIn = null;
235	StringTokenizer str;
236	String item, oneLine;
237	// to control if the minimum necessary 3 parameters are given in file
238	int cfgParsPresent=0;
239	// setting default blank values for port and dbname, they are set to blank unless fields specified in file
240	port="";
241	dbname="";
242	// list the entries in the file and decompose them
243	try {
244	fileIn = new BufferedReader(new FileReader(new File(connFile))); // open BufferedReader to file connFile
245	while ((oneLine = fileIn.readLine()) != null ) {
246	// Construct a stringTokenizer for the line that we read with : delimited
247	str = new StringTokenizer(oneLine, "="); // true sets returnDelimiters flag
248	while ( str.hasMoreTokens()) {
249	item = str.nextToken();
250	if( item.equals("host")) { // mandatory parameter
251	host=str.nextToken();
252	cfgParsPresent++;
253	break;
254	} // end if host
255	if( item.equals("port")) { // optional parameter
256	port=":"+str.nextToken();
257	break;
258	} // end if port
259	if( item.equals("user")) { // mandatory parameter
260	user=str.nextToken();
261	cfgParsPresent++;
262	break;
263	} // end if password
264	if( item.equals("password")) { // mandatory parameter
265	password=str.nextToken();
266	cfgParsPresent++;
267	break;
268	} // end if password
269	if( item.equals("database")) { // optional parameter
270	dbname=str.nextToken();
271	break;
272	} // end if password
273	} // next token in this line
274	} // next line in the file
275	if (cfgParsPresent<3){
276	System.err.println("Not all mandatory parameters are given in connection file "+connFile+". Can't connect to mysql server, exiting.");
277	System.exit(1);
278	}
279	}
280	catch (IOException e) {
281	System.err.println("Couldn't open file "+connFile);
282	e.printStackTrace();
283	System.exit(1);
284	}
285
286	try { // closing the file
287	if (fileIn != null) fileIn.close();
288	} catch (IOException e) {
289	System.err.println("Couldn't close file "+connFile);
290	e.printStackTrace();
291	}
292
293	}
294
295	/**
296	* To print the db size info for the given db of this MySQLConnection.
297	* @param dbName
298	*/
299	public void printDbSizeInfo (String dbName) {
300	double data = 0, index = 0, table_data = 0, table_index = 0, GB = Math.pow(2, 30);
301	String Query = null, table = null;
302	Statement Stmt = null;
303	ResultSet RS = null;
304	try {
305	Query = "SHOW TABLE STATUS FROM "+dbName;
306	Stmt = this.conn.createStatement();
307	RS = Stmt.executeQuery(Query);
308	while (RS.next()) {
309	table = RS.getString("Name");
310	table_data = RS.getDouble("Data_length");
311	table_index = RS.getDouble("Index_length");
312	data += RS.getDouble("Data_length");
313	index += RS.getDouble("Index_length");
314	System.out.println("Table "+table+"##data:"+table_data+", index:"+table_index);
315	}
316	RS.close();
317	Stmt.close();
318	System.out.println("Database "+dbName+" needs "+((data+index)/GB)+ " GB (data:"+(data/GB)+", index:"+(index/GB)+").");
319	}
320	catch (SQLException e) {
321	System.err.println("SQLException: " + e.getMessage());
322	System.err.println("SQLState: " + e.getSQLState());
323	System.err.println("VendorError: " + e.getErrorCode());
324	e.printStackTrace();
325	} // end try/catch connection
326	}
327
328	/**
329	* To get range of a column from a table in this MySQLConnection. Note that if the connection was created without pointing
330	* to a particular database then the argument table must be specified as dbname.tablename.
331	* @param table
332	* @param column
333	* @return
334	*/
335	public double[] getRange(String table, String column) {
336	String query = "";
337	Statement S;
338	ResultSet R;
339	double[] range = new double[2];
340	try {
341	query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+";";
342	S = this.conn.createStatement();
343	R = S.executeQuery(query);
344	if (R.next()) {
345	range[0] = R.getDouble(1);
346	range[1] = R.getDouble(2);
347	}
348	R.close();
349	S.close();
350	} // end try
351	catch (SQLException e) {
352	System.err.println("SQLException: " + e.getMessage());
353	System.err.println("SQLState: " + e.getSQLState());
354	System.err.println("VendorError: " + e.getErrorCode());
355	e.printStackTrace();
356	} // end catch
357	return range;
358	}
359
360	/**
361	* To get range of a column from a table in this MySQLConnection using a given WHERE condition. Note that if
362	* the connection was created without pointing to a particular database then the argument table must
363	* be specified as dbname.tablename.
364	* @param table
365	* @param column
366	* @param whereStr
367	* @return
368	*/
369	public double[] getRange(String table, String column, String whereStr) {
370	String query = "";
371	Statement S;
372	ResultSet R;
373	double[] range = new double[2];
374	try {
375	query = "SELECT MIN("+column+"), MAX("+column+") FROM "+table+" WHERE ("+whereStr+");";
376	S = this.conn.createStatement();
377	R = S.executeQuery(query);
378	if (R.next()) {
379	range[0] = R.getDouble(1);
380	range[1] = R.getDouble(2);
381	}
382	R.close();
383	S.close();
384	} // end try
385	catch (SQLException e) {
386	System.err.println("SQLException: " + e.getMessage());
387	System.err.println("SQLState: " + e.getSQLState());
388	System.err.println("VendorError: " + e.getErrorCode());
389	e.printStackTrace();
390	} // end catch
391	return range;
392	}
393
394	/**
395	* To get all indexes for a certain table. Note the MySQLConnection object must be created with a non-blank database.
396	* @param table
397	* @return
398	*/
399	public String[] getAllIndexes4Table(String table) {
400	ArrayList<String> indexesAL=new ArrayList<String>();
401	String query;
402	Statement S;
403	ResultSet R;
404	try {
405	query = "SELECT index_name from INFORMATION_SCHEMA.statistics WHERE table_schema='"+dbname+"' AND table_name='"+table+"';";
406	S = this.conn.createStatement();
407	R = S.executeQuery(query);
408	while (R.next()) {
409	indexesAL.add(R.getString(1));
410	}
411	R.close();
412	S.close();
413	} // end try
414	catch (SQLException e) {
415	System.err.println("SQLException: " + e.getMessage());
416	System.err.println("SQLState: " + e.getSQLState());
417	System.err.println("VendorError: " + e.getErrorCode());
418	e.printStackTrace();
419	} // end catch
420	String[] indexes=new String[indexesAL.size()];
421	int i=0;
422	for (String index:indexesAL) {
423	indexes[i]=index;
424	i++;
425	}
426	return indexes;
427	}
428	}