标签：man while select 增删改查 nec down 类型 values console
最近要做一个单机小程序，但涉及到一些数据的存取和增删改查，研究了一番，觉得还是轻量级数据库sqlite最合适，于是先做了个样例，方便进一步开发。
sqlite可以在如下网址下载
https://www.sqlite.org/download.html
但可直接下载System.Data.SQLite用在c#中，在如下网址下载
http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki
我选择了其中的Precompiled Binaries for 64-bit Windows (.NET Framework 4.0)
sqlite-netFx40-binary-bundle-x64-2010-1.0.113.0.zip
不过貌似需要tunnel cross great wall。也可下载我文末的样例程序包，里面已经包含了必要的库及帮助文件。
新建工程，因为下载的是64位SQLite库，在配制管理器中修改工程为x64架构。
然后引用中添加System.Data.SQLite.dll即可使用。
程序本身比较简单，核心是下面的SQLite帮助类，用于封装一些函数，便于调用。直接上代码，每个函数都有注释，也比较简单。
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace SQLiteDemo
{
public enum SQLiteType
{
INTEGER,
REAL,
TEXT,
BLOB
}
class SQLiteHelper
{
string m_connString;
public SQLiteHelper(string databasepath)
{
m_connString = "data source = " + databasepath;
if (!File.Exists(databasepath))
{
SQLiteConnection.CreateFile(databasepath);
}
}
/// <summary>
/// 执行不带参数的SQL语句
/// </summary>
/// <param name="cmdString">SQL语句</param>
/// <returns>受影响的行数</returns>
public int Execute(string cmdString)
{
using (SQLiteConnection conn = new SQLiteConnection(m_connString))
{
using (SQLiteCommand command = new SQLiteCommand(cmdString, conn))
{
try
{
conn.Open();
int row = command.ExecuteNonQuery();
return row;
}
catch (SQLiteException e)
{
conn.Close();
throw new Exception(e.Message);
}
}
}
}
/// <summary>
/// 批量执行SQL语句
/// </summary>
/// <param name="cmdStrings">要批量执行的所有SQL语句</param>
public void BatchExecute(string[] cmdStrings)
{
using (SQLiteConnection conn = new SQLiteConnection(m_connString))
{
conn.Open();
SQLiteTransaction trans = conn.BeginTransaction();
SQLiteCommand command = new SQLiteCommand(conn);
command.Transaction = trans;
try
{
for (int i = 0; i < cmdStrings.Length; i++)
{
command.CommandText = cmdStrings[i];
command.ExecuteNonQuery();
}
trans.Commit();
}
catch (SQLiteException e)
{
trans.Rollback();
throw new Exception(e.Message);
}
}
}
/// <summary>
/// 创建数据表
/// </summary>
/// <param name="tableName">数据表名</param>
/// <param name="colNames">所有列名称</param>
/// <param name="colTypes">每一列的类型</param>
/// <param name="infos">每一列的其他描述，比如是否可为NULL，是否为主键</param>
/// <returns>返回数据表Reader</returns>
public SQLiteDataReader CreateTable(string tableName, string[] colNames, SQLiteType[] colTypes, string[] infos = null)
{
string cmd = "CREATE TABLE IF NOT EXISTS " + tableName + "( ";
for (int i = 0; i < colNames.Length; i++)
{
cmd += colNames[i] + " " + colTypes[i].ToString();
if (infos != null)
{
cmd += " " + infos[i];
}
if (i != colNames.Length - 1)
{
cmd += ", ";
}
}
cmd += " )";
return Select(cmd);
}
/// <summary>
/// 删除数据表
/// </summary>
/// <param name="tableName">要删除的数据表</param>
/// <returns>该表的行数</returns>
public int DropTable(string tableName)
{
string cmd = "DROP TABLE " + tableName;
return Execute(cmd);
}
/// <summary>
/// 在数据表中插入数据，但不适用于插入二进制数据
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="types">每一列的类型</param>
/// <param name="values">每一列的值</param>
/// <param name="columns">可选参数，每一列的列名</param>
/// <returns>插入的行数</returns>
public int InsertData(string tableName, SQLiteType[] types, string[] values, string[] columns = null)
{
string cmd = "INSERT INTO " + tableName;
if (columns != null)
{
cmd += " ( ";
for (int i = 0; i < columns.Length; i++)
{
cmd += columns[i];
if (i != columns.Length - 1)
{
cmd += ", ";
}
}
cmd += " ) ";
}
cmd += " VALUES ( ";
for (int i = 0; i < values.Length; i++)
{
switch (types[i])
{
case SQLiteType.INTEGER:
case SQLiteType.REAL:
cmd += values[i];
break;
case SQLiteType.BLOB:
throw new Exception("Please use InsertBinary to do the job!");
default:
cmd += "‘" + values[i] + "‘";
break;
}
if (i != values.Length - 1)
{
cmd += ", ";
}
}
cmd += " )";
return Execute(cmd);
}
/// <summary>
/// 执行带参数的SQL语句
/// </summary>
/// <param name="cmdString">带参数的SQL语句</param>
/// <param name="parameters">对应的参数</param>
/// <returns>受影响的行数