1.     hsql 学习
1.1.     学习目的
本文档是针对hSQL 数据库方面的基础学习åQŒäؓ了ä‹É™å¹ç›®¾l„成员能够达åˆîC‹É用hSQL 数据库的目的ã€?br />1.2.     培训对象
开发ähå‘?br />1.3.     常用词及½W¦å·è¯´æ˜Ž
常用词：
hsqlåQšä¸€¿Uå…è´¹çš„è·¨åã^台的数据库系¾l?br />E:\hsqldbåQšè¡¨½Cºæ˜¯åœ¨dos 命ä×o½H—口下面
1.4.     参考信�br />doc\guide\guide.pdf

2.     HSQL
2.1.     HSQL ˜qè¡Œå·¥å…·
java -cp ../lib/hsqldb.jar org.hsqldb.util.DatabaseManager
注意hsqldb.jar æ–‡äšg的文件èµ\å¾?最好能攑ֈ°classpath 里面,或者放到当前èµ\径下.
java -cp hsqldb.jar org.hsqldb.util.DatabaseManager

2.2.     ˜qè¡Œæ•°æ®åº?br />启动方式: Server Modes and
In-Process Mode (also called Standalone Mode).

一个test 数据库会包含如下文äšg:
�test.properties
�test.script
�test.log
�test.data
�test.backup
test.properties æ–‡äšg包含关于数据库的一般设¾|?
test.script   æ–‡äšg包含表和其它数据åº?插入没有¾~“存表的数据.
test.log æ–‡äšg包含当前数据库的变更.
test.data æ–‡äšg包含¾~“存表的数据
test.backup æ–‡äšg是最˜q‘持久化状态的表的数据文äšg的压¾~©å¤‡ä»½æ–‡ä»?br />所有以上这个文仉™ƒ½æ˜¯å¿…要的,不能被删é™?如果数据库没有缓存表,test.data å’Œtest.backup æ–‡äšgž®†ä¸ä¼šå­˜åœ?另外,除了以上文äšgHSQLDB 数据库可以链接到ä»ÖM½•æ–‡æœ¬æ–‡äšg,比如cvs æ–‡äšg.

当操作test 数据库的时å€? test.log 用于保存数据的变æ›? 当正常SHUTDOWN,˜q™ä¸ªæ–‡äšgž®†è¢«åˆ é™¤. 否则(不是正常shutdown),˜q™ä¸ªæ–‡äšgž®†ç”¨äºŽå†‹Æ¡å¯åŠ¨çš„æ—¶å€?重做˜q™äº›å˜æ›´.test.lck æ–‡äšg也用于记录打开的数据库的事å®? 正常SHUTDOWN,æ–‡äšg也被删除.在一些情况下,test.data.old æ–‡äšg会被创徏,òq¶åˆ é™¤ä»¥å‰çš„.






2.3.     Server Mode
java -cp ../lib/hsqldb.jar org.hsqldb.Server -database.0 file:mydb -dbname.0 xdb

命ä×o行方å¼?


启动数据,数据库文件mydb,数据库名¿U°xdb

也可以在 server.properties æ–‡äšg中定义启动的数据åº?最å¤?0ä¸?br />例如: server.properties:
server.database.0=file:E:/hsqldb/data/mydb
server.dbname.0=xdb

server.database.1=file:E:/hsqldb/data/testdb
server.dbname.1=testdb

server.database.2=mem:adatabase
server.dbname.2=quickdb
启动命ä×o: java -cp ../lib/hsqldb.jar org.hsqldb.Server
˜qè¡Œ¾l“果如下



java ‹¹‹è¯•½E‹åº:
package test;
import junit.framework.TestCase;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class TestConnect extends TestCase {
     Connection connection;
     protected void setUp()
     {        
         try {
             Class.forName("org.hsqldb.jdbcDriver" );
             connection = DriverManager.getConnection("jdbc:hsqldb:hsql://localhost/xdb","sa","");
            
            
         } catch (Exception e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }
     public void testselect()
     {
         Statement stmt=null;
         ResultSet rs=null;
         try {
             stmt = connection.createStatement();
             String sql ="select * from test";
             rs=stmt.executeQuery( sql);
             while(rs.next() )
             {
                 System.out.println("id="+rs.getString("id"));
                 System.out.println("name="+rs.getString("name"));
             }
            
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         finally
         {
             try {
                 rs.close() ;
                 stmt.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }            
         }    
        
     }
     protected void tearDown()
     {
         try {
             connection.close();
         } catch (Exception e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }

}
以上在eclipse 中测试通过.

2.4.     In-Process (Standalone) Mode
不需要启动server
connection = DriverManager.getConnection("jdbc:hsqldb:file:E:/hsqldb/data/mydb","sa","");
˜q™æ ·ž®±å¯ä»¥è¿žæŽ¥æ•°æ®åº“ã€?br />只能在一个jvm 中ä‹É用，不能在多个jvm 中ä‹É用ã€?br />˜q™ç§æ¨¡å¼æ˜¯åœ¨ç›¸åŒçš„jvm 下作ä¸ÞZ½ çš„应用程序的一部分åQŒè¿è¡Œæ•°æ®åº“引擎。对大多数应用程序，˜q™ç§æ¨¡å¼˜qè¡Œä¼šç›¸å½“å¿«åQŒä½œä¸ºæ•°æ®ï¼Œä¸éœ€è¦è{换和¾|‘络传输ã€?br />
主要的缺点就是不可能从外面的应用½E‹åºè®‰K—®åˆ°é»˜è®¤æ•°æ®åº“åQŒå› æ­¤å½“你的应用˜qè¡Œæ—¶å€™ï¼Œä½ ä¸èƒ½é€šè¿‡åˆ«çš„工具‹‚€æŸ¥æ•°æ®åº“内容。在1.8.0 版本ä¸?你可以在相同jvm 中的¾U¿ç¨‹ä¸­è¿è¡Œæ•°æ®åº“初始化，òq¶æä¾›å¤–面访问你的进½E‹å†…数据库ã€?br />     推荐在开发应用中使用˜q™ç§æ–¹å¼ã€?br />˜qžæŽ¥ä¸ÔŒ¼š
Windows: DriverManager.getConnection("jdbc:hsqldb:file:E:/hsqldb/data/mydb","sa","");
Unix: DriverManager.getConnection("jdbc:hsqldb:file:/opt/db/testdb","sa","");

2.5.     Memory-Only Databases
当随卌™®¿é—®å†…存，数据库不固定æ—Óž¼Œå¯ä»¥é‡‡ç”¨å†…存的方式运行数据库åQŒç”±äºŽæ²¡æœ‰æ•°æ®å†™åˆ°ç¡¬ç›˜ä¸ŠåQŒè¿™¿Uæ–¹å¼ä‹É用在应用数据和applets 和特ŒDŠåº”用的内部˜q›ç¨‹ä¸­ä‹É用，URLåQ?br />
Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:aname", "sa", "");
2.6.     Using Multiple Databases in One JVM
2.7.     Different Types of Tables
HSQLDB 支持 TEMP 表和三种¾cÕdž‹çš„持久表åQˆMEMORY è¡? CACHED 表，TEXT表）

当ä‹Éç”?CREATE TABLE   命ä×oæ—Óž¼ŒMemory 表时默认¾cÕdž‹åQŒå®ƒä»¬çš„数据整体保存在内存当中，但是ä»ÖM½•æ”¹å˜å®ƒä»¬çš„结构或者内容，它们会被写到<dbname>.script æ–‡äšg中。这个脚本文件在数据库下一‹Æ¡æ‰“开的时候被对出åQŒå†…存表重新被创建内容，根temp 表不同，内存表时持久化的ã€?br />
CACHED 表通过CREATE CACHED TABLE 命ä×o建立. 只有部分的它们的数据或者烦引被保存在内存中åQŒå…è®¸å¤§è¡¨å ç”¨å‡ ç™‘Ö…†çš„内存空间。例外一个优点，在数据库引擎中，启动大量数据的缓存表需要花费少量的旉™—´åQŒç¼ºç‚ÒŽ˜¯å‡æ…¢äº†è¿è¡Œå’Œä½¿ç”¨Hsqldb 的速度。表相对ž®çš„时候，不要使用cache 表，在小表中使用内存数据库ã€?br />
从版æœ?1.7.0 以后åQŒæ”¯æŒtext 表，使用 CSV (Comma Separated Value)   或者其它分隔符文本文äšg作äؓ它们的数据源。你可以ç‰ÒŽ®ŠæŒ‡å®šä¸€ä¸ªå­˜åœ¨çš„CSV æ–‡äšgåQŒä¾‹å¦‚从其它的数据或者程序中导出文äšgåQŒä½œä¸ºTXT 表的数据源ã€?同时,你可以指定一个空文äšgåQŒé€šè¿‡æ•°æ®åº“引擎填充数据。TEXT 表将比cache 表更加效率高。Text 表可以指向不同的数据文äšgã€?br />
* memory-only databases 数据库只支持memory 表和cache 表，不支持text 表ã€?br />2.8.     ¾U¦æŸå’Œçƒ¦å¼?br />HSQLDB 支持 PRIMARY KEY, NOT NULL, UNIQUE, CHECK and FOREIGN KEY ¾U¦æŸ.





3.     sql 命ä×o
3.1.     sql 支持
select top 1 * from test;
select limit 0 2 * from test;
DROP TABLE test IF EXISTS;
3.2.     Constraints and Indexes
ä¸Õd¥¾U¦æŸåQšPRIMARY KEY
唯一¾U¦æŸåQ?br />唯一索引åQ?br />外健åQ?br />CREATE TABLE child(c1 INTEGER, c2 VARCHAR, FOREIGN KEY (c1, c2) REFERENCES parent(p1, p2));

3.3.     索引和查询速度
索引提高查询速度åQŒæ¯”提高排序速度ã€?br />ä¸Õd¥å’Œå”¯ä¸€æ‰€åˆ—自动创建烦引，否则需要自己创建CREATE INDEX commandã€?br />索引åQ?唯一索引和非唯一索引
多列的烦引，如果只是使用后面的，不ä‹É用第一个，ž®†ä¸ä¼šæ¡æŸ¥è¯¢é€Ÿåº¦ã€?br />
(TB is a very large table with only a few rows where TB.COL3 = 4)
SELECT * FROM TA JOIN TB ON TA.COL1 = TB.COL2 AND TB.COL3 = 4;
SELECT * FROM TB JOIN TA ON TA.COL1 = TB.COL2 AND TB.COL3 = 4;(faster)

原因�TB.COL3 可以被快速的估计,如果TB 表放到前�index on TB.COL3):
一般规则是把羃ž®æ¡ä»¶çš„列的表放在前é?br />
3.4.     使用where ˜q˜æ˜¯join
使用 WHERE   条äšg链接表可能会降低˜qè¡Œé€Ÿåº¦.
下面的例子将会比较慢,即ä‹É使用了烦å¼?
     SELECT ... FROM TA, TB, TC WHERE TC.COL3 = TA.COL1 AND TC.COL3=TB.COL2 AND TC.COL4 = 1
˜q™ä¸ªæŸ¥è¯¢éšå«TA.COL1 = TB.COL2 ,但是没有直接讑֮š˜q™ä¸ªæ¡äšg.如果 TA å’?TB 每个表都包含100 条记å½?10000 ¾l„合ž®†å’Œ TC å…Œ™”,用于TC˜q™ä¸ªåˆ—的条äšg,ž®½ç®¡æœ‰çƒ¦å¼•åœ¨˜q™ä¸ªåˆ—上.使用JOIN 关键å­? 在组合TC 之前,TA.COL1 = TB.COL2 条äšg直接òq¶ç¾ƒž®ç»„å?TA å’?TB çš„è¡Œæ•? 在运行大数据量的表的¾l“æžœæ˜?ž®†ä¼šå¾ˆå¿«:
     SELECT ... FROM TA JOIN TB ON TA.COL1 = TB.COL2 JOIN TC ON TB.COL2 = TC.COL3 WHERE TC.COL4 = 1
˜q™ä¸ªæŸ¥è¯¢å¯ä»¥æé«˜ä¸€å¤§æ­¥,如果改变表的™åºåº, 所ä»?TC.COL1 = 1 ž®†æœ€å…ˆä‹Éç”?˜q™æ ·æ›´å°çš„集合将¾l„合在一èµ?
     SELECT ... FROM TC JOIN TB ON TC.COL3 = TB.COL2 JOIN TA ON TC.COL3 = TA.COL1 WHERE TC.COL4 = 1
以上例子,数据引擎自动应用于TC.COL4 = 1 ¾l„合ž®çš„集合于其它表兌™”. Indexes TC.COL4, TB.COL2   TA.COL1 都将使用索引,提高查询速度.
3.5.     Subqueries and Joins
使用join 和调整表的顺序提高效�
例如:, ½W¬äºŒä¸ªæŸ¥è¯¢çš„速度ž®†æ›´å¿«ä¸€äº?TA.COL1 å’ŒTB.COL3都有索引):
Example 2.2. Query comparison
     SELECT ... FROM TA WHERE TA.COL1 = (SELECT MAX(TB.COL2) FROM TB WHERE TB.COL3 = 4)

     SELECT ... FROM (SELECT MAX(TB.COL2) C1 FROM TB WHERE TB.COL3 = 4) T2 JOIN TA ON TA.COL1 = T2.C1
½W¬äºŒä¸ªæŸ¥è¯¢å°† MAX(TB.COL2) 与一个单记录表相兌™”. òq¶ä‹É用TA.COL1索引,˜q™å°†å˜å¾—非常å¿? ½W¬ä¸€ä¸ªæŸ¥è¯¢æ˜¯ž®?TA 表中的每一条记录不断地与MAX(TB.COL2)匚w….
3.6.     数据¾cÕdž‹
TINYINT, SMALLINT, INTEGER, BIGINT, NUMERIC and DECIMAL (without a decimal point) are supported integral types and map to byte, short, int, long and BigDecimal in Java.

Integral Types:
TINYINT, SMALLINT, INTEGER, BIGINT, NUMERIC and DECIMAL
Other Numeric Types:
REAL, FLOAT or DOUBLE
Bit and Boolean Types:
     BOOLEAN: UNDEFINED,TRUE,FALSE  
NULL values are treated as undefined.
Storage and Handling of Java Objects
Sequences and Identity

Identity Auto-Increment Columns:
The next IDENTITY value to be used can be set with the
ALTER TABLE ALTER COLUMN <column name> RESTART WITH <new value>;
Sequences:
SELECT NEXT VALUE FOR mysequence, col1, col2 FROM mytable WHERE ...
    
3.7.     事务问题:
SET PROPERTY "sql.tx_no_multi_rewrite" TRUE

4.     Connections
通用驱动jdbc:hsqldb:   下列协议标识(mem: file: res: hsql: http: hsqls: https:)
Table 4.1. Hsqldb URL Components
Driver and Protocol     Host and Port     Database
jdbc:hsqldb:mem:
     not available     accounts

jdbc:hsqldb:mem:.
jdbc:hsqldb:file:
     not available     mydb
/opt/db/accounts
C:/data/mydb

数据库èµ\å¾?
jdbc:hsqldb:res:
     not available     /adirectory/dbname

jars files are accessed in Java programs. The /adirectory above stands for a directory in one of the jars.
jdbc:hsqldb:hsql:
jdbc:hsqldb:hsqls:
jdbc:hsqldb:http:
jdbc:hsqldb:https:
     //localhost
//192.0.0.10:9500
//dbserver.somedomain.com
     /an_alias
/enrollments
/quickdb

别名在server.properties or webserver.propertiesæ–‡äšg中指å®?br />     database.0=file:/opt/db/accounts
     dbname.0=an_alias

     database.1=file:/opt/db/mydb
     dbname.1=enrollments

     database.2=mem:adatabase
     dbname.2=quickdb
In the example below, the database files lists.* in the /home/dbmaster/ directory are associated with the empty alias:
     database.3=/home/dbmaster/lists
     dbname.3=
4.1.     Connection properties
Connection properties are specified either by establishing the connection via the:
     DriverManager.getConnection (String url, Properties info);
method call, or the property can be appended to the full Connection URL.
Table 4.2. Connection Properties
get_column_name     true     column name in ResultSet
This property is used for compatibility with other JDBC driver implementations. When true (the default), ResultSet.getColumnName(int c) returns the underlying column name
When false, the above method returns the same value as ResultSet.getColumnLabel(int column) Example below:
     jdbc:hsqldb:hsql://localhost/enrollments;get_column_name=false
                    
When a ResultSet is used inside a user-defined stored procedure, the default, true, is always used for this property.
ifexists     false     connect only if database already exists
Has an effect only with mem: and file: database. When true, will not create a new database if one does not already exist for the URL.
When false (the default), a new mem: or file: database will be created if it does not exist.
Setting the property to true is useful when troubleshooting as no database is created if the URL is malformed. Example below:
     jdbc:hsqldb:file:enrollments;ifexists=true
shutdown     false     shut down the database when the last connection is closed
This mimics the behaviour of 1.7.1 and older versions. When the last connection to a database is closed, the database is automatically shut down. The property takes effect only when the first connection is made to the database. This means the connection that opens the database. It has no effect if used with subsequent, simultaneous connections.
This command has two uses. One is for test suites, where connections to the database are made from one JVM context, immediately followed by another context. The other use is for applications where it is not easy to configure the environment to shutdown the database. Examples reported by users include web application servers, where the closing of the last connection conisides with the web app being shut down.


4.2.     Properties Files
大小写敏�(e.g. server.silent=FALSE will have no effect, but server.silent=false will work).
属性文件和讑֮šå­˜å‚¨å¦‚下 :
Table 4.3. Hsqldb Server Properties Files
File Name     Location     Function
server.properties     the directory where the command to run the Server class is issued     settings for running HSQLDB as a database server communicating with the HSQL protocol
webserver.properties     the directory where the command to run the WebServer class is issued     settings for running HSQLDB as a database server communicating with the HTTP protocol
<dbname>.properties     the directory where all the files for a database are located     settings for each particular database
Properties files for running the servers are not created automatically. You should create your own files that contain server.property=value pairs for each property.
4.2.1.     Server and Web Server Properties
server.properties and webserver.properties æ–‡äšg支持如下讑֮š:
Table 4.4. Property File Properties
Value     Default     Description
server.database.0     test     the path and file name of the first database file to use
server.dbname.0     ""     lowercase server alias for the first database file
server.urlid.0     NONE     SqlTool urlid used by UNIX init script. (This property is not used if your are running Server/Webserver on a platform other than UNIX, or of you are not using our UNIX init script).
server.silent     true     no extensive messages displayed on console
server.trace     false     JDBC trace messages displayed on console
In 1.8.0, 每个服务器支持同时启�0个不同的数据� The server.database.0 property defines the filename / path whereas the server.dbname.0 defines the lowercase alias used by clients to connect to that database. The digit 0 is incremented for the second database and so on. Values for the server.database.{0-9} property can use the mem:, file: or res: prefixes and properties as discussed above under CONNECTIONS. For example,
     database.0=mem:temp;sql.enforce_strict_size=true;
Values specific to server.properties are:
Table 4.5. Server Property File Properties
Value     Default     Description
server.port     9001     TCP/IP port used for talking to clients. All databases are served on the same port.
server.no_system_exit     true     no System.exit() call when the database is closed
Values specific to webserver.properties are:
Table 4.6. WebServer Property File Properties
Value     Default     Description
server.port     80     TCP/IP port used for talking to clients
server.default_page     index.html     the default web page for server
server.root     ./     the location of served pages
.<extension>     ?     multiple entries such as .html=text/html define the mime types of the static files served by the web server. See the source for WebServer.java for a list.
All the above values can be specified on the command line to start the server by omitting the server. prefix.
5.     SqlTool
Mem 数据�
E:\hsqldb>java -jar ./lib/hsqldb.jar mem
Hsql Server:
(前提是xdb server 已经启动):
(java -cp ../lib/hsqldb.jar org.hsqldb.Server -database.0 file:mydb -dbname.0 xdb)
java -jar ./hsqldb.jar xdb