C#/Java连接sqlite与使用技巧_C#教程

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1)下载sqlite jdbc驱动http://www.xerial.org/maven/repository/artifact/org/xerial/sqlite-jdbc/

2)将下载的驱动加入eclipse项目的built path中

3)示例代码:


package com.hedalixin;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

public class test {

    /**
     * @param args
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        Class.forName("org.sqlite.JDBC");
        Connection conn = DriverManager.getConnection("jdbc:sqlite:test.db");
        Statement stat = conn.createStatement();
        stat.executeUpdate("drop table if exists people;");
        stat.executeUpdate("create table people (name, occupation);");
        PreparedStatement prep = conn
                .prepareStatement("insert into people values (?, ?);");

        prep.setString(1, "Gandhi");
        prep.setString(2, "politics");
        prep.addBatch();
        prep.setString(1, "Turing");
        prep.setString(2, "computers");
        prep.addBatch();
        prep.setString(1, "Wittgenstein");
        prep.setString(2, "smartypants");
        prep.addBatch();
        conn.setAutoCommit(false);
        prep.executeBatch();
        conn.setAutoCommit(true);
        ResultSet rs = stat.executeQuery("select * from people;");
        while (rs.next()) {
            System.out.println("name = " + rs.getString("name"));
            System.out.println("job = " + rs.getString("occupation"));
        }
        rs.close();
        conn.close();

    }
}

2.  C#连接sqlite
2.1 使用SQLITE.NET
SQLite.NET也是一个数据访问组件,其中的System.Data.SQLite 就好像是.NET自带的System.Data.SqlClient一样。里面包含了connection、command等数据访问的常用对象,只是他们前面都有一个前缀sqlite。
1)下载System.Data.SQLite,下载地址http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki

2)  通过Add References引用SQLite ADO .NET安装目录的bin目录下的System.Data.SQLite.DLL。

3)创建表、读取数据等和Access或MS SQL没多大区别


//创建一个数据库文件
string datasource="h:/test.db";
System.Data.SQLite.SQLiteConnection.CreateFile(datasource);
//连接数据库
System.Data.SQLite.SQLiteConnection conn = new System.Data.SQLite.SQLiteConnection();
System.Data.SQLite.SQLiteConnectionStringBuilder connstr = new System.Data.SQLite.SQLiteConnectionStringBuilder();
connstr.DataSource = datasource;
connstr.Password = "admin";//设置密码,SQLite ADO.NET实现了数据库密码保护
conn.ConnectionString = connstr.ToString();            
conn.Open();
//创建表
System.Data.SQLite.SQLiteCommand cmd = new System.Data.SQLite.SQLiteCommand();
string sql = "CREATE TABLE test(username varchar(20),password varchar(20))";
cmd.CommandText=sql;
cmd.Connection=conn;
cmd.ExecuteNonQuery();
//插入数据
sql = "INSERT INTO test VALUES('ekinglong','mypassword')";
cmd.CommandText = sql;
cmd.ExecuteNonQuery();
//取出数据
sql = "SELECT * FROM test";
cmd.CommandText = sql;
System.Data.SQLite.SQLiteDataReader reader = cmd.ExecuteReader();
StringBuilder sb = new StringBuilder();
while (reader.Read())
{
     sb.Append("username:").Append(reader.GetString(0)).Append("\n")
     .Append("password:").Append(reader.GetString(1));

 }
 MessageBox.Show(sb.ToString());

2.2使用原生态的ADO.NET访问SQLite


using (DbConnection conn = new SQLiteConnection( System.Configuration.ConfigurationManager.ConnectionStrings["sqlite"].ConnectionString))
{
    conn.Open();
    DbCommand comm = conn.CreateCommand();
    comm.CommandText = "select * from customer";
    comm.CommandType = CommandType.Text;
    using (IDataReader reader = comm.ExecuteReader())
    {
        while (reader.Read())
        {
            Response.Write(reader[0]);
        }
    }
}

SQLite.NET数据库连接字符串ConnectionString格式:
Basic(基本的)
      Data Source=filename;Version=3;
Using UTF16(使用UTF16编码)
      Data Source=filename;Version=3;UseUTF16Encoding=True;
With password(带密码的)
      Data Source=filename;Version=3;Password=myPassword;
Using the pre 3.3x database format(使用3.3x前数据库格式)
      Data Source=filename;Version=3;Legacy Format=True;
Read only connection(只读连接)
      Data Source=filename;Version=3;Read Only=True;
With connection pooling(设置连接池)
      Data Source=filename;Version=3;Pooling=False;Max Pool Size=100;
Using DateTime.Ticks as datetime format()
      Data Source=filename;Version=3;DateTimeFormat=Ticks;
      The default value is ISO8601 which activates the use of the ISO8601 datetime format
Store GUID as text(把Guid作为文本存储,默认是Binary)
     Data Source=filename;Version=3;BinaryGUID=False;
      如果把Guid作为文本存储需要更多的存储空间
Specify cache size(指定Cache大小)
      Data Source=filename;Version=3;Cache Size=2000;
      Cache Size 单位是字节
Specify page size(指定页大小)
      Data Source=filename;Version=3;Page Size=1024;
      Page Size 单位是字节
Disable enlistment in distributed transactions
      Data Source=filename;Version=3;Enlist=N;
Disable create database behaviour(禁用创建数据库行为)
      Data Source=filename;Version=3;FailIfMissing=True;
      默认情况下,如果数据库文件不存在,会自动创建一个新的,使用这个参数,将不会创建,而是抛出异常信息
Limit the size of database(限制数据库大小)
      Data Source=filename;Version=3;Max Page Count=5000;
      The Max Page Count is measured in pages. This parameter limits the maximum number of pages of the database.
Disable the Journal File (禁用日志回滚)
      Data Source=filename;Version=3;Journal Mode=Off;
      This one disables the rollback journal entirely.
Persist the Journal File(持久)
      Data Source=filename;Version=3;Journal Mode=Persist;
      This one blanks and leaves the journal file on disk after a commit. Default behaviour is to delete the Journal File after each commit.
Controling file flushing
      Data Source=filename;Version=3;Synchronous=Full;
      Full specifies a full flush to take action after each write. Normal is the default value. Off means that the underlying OS flushes I/O's.

 

Sqlite使用技巧
1 .Sqlite判断数据表是否存在
SELECT COUNT(*)  as CNT FROM sqlite_master where type='table' and name='DBInfo' //其中DBInfo为需要判断的表名。注意大小写敏感!


2. SQLite一条SQL语句插入多条记录
INSERT INTO TABLE(col1, col2) SELECT val11, val12 UNION ALL SELECT val21, val22 ;
这样的写法是属于复合SQL语句,表示先把两个SELECT的结果集进行无删减的联合,再把联合结果插入到TABLE中。

3. sqlite事务
是以文件的形式存在磁盘中,每次访问时都要打开一次文件,如果对数据进行大量操作时,会很慢~
解决办法是用事务的形式提交:因为我们开始事务后,进行大量操作的语句都保存在内存中,当提交时才全部写入数据库,此时,数据库文件也就只用打开一次。
sql语句:
begin;  
INSERT INTO "table" VALUES ('a', 'b', 'c');  
INSERT INTO "table" VALUES ('a', 'b', 'c');  
INSERT INTO "table" VALUES ('a', 'b', 'c');  
commit;
4. SQLite自增ID字段使用方法为      INTEGER PRIMARY KEY AUTOINCREMENT
5. 分页查询显示
类似MySQL数据库 ,是利用mySQL的LIMIT函数,LIMIT [offset,] rows从数据库表中M条记录开始检索N条记录的语句为:
SELECT * FROM 表名称 LIMIT M,N
例如从表Sys_option(主键为sys_id)中从10条记录开始检索20条记录,语句如下:
select * from sys_option limit 10,20

 

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