20100626 学习记录：奇怪的stringbuilder && 过滤字符串中的非数字字符 && C#中Trim()、TrimStart()、TrimEnd()的错误认识
之前用stringbuilder动态建sql的时候，写过这样的sql
StringBuilder sqlBuilder = new StringBuilder();
sqlBuilder.Append(" INSERT INTO ");
sqlBuilder.Append(" @TABLENAME ");
sqlBuilder.Append(" (AppID,Buffer) ");
sqlBuilder.Append(" VALUES( ");
sqlBuilder.Append(" @APPID, @BUFFER ");
sqlBuilder.Append(" ) ");
sqlStr = sqlBuilder.ToString();
ArrayList paramList = new ArrayList();
paramList.Add(new SqlParameter("@TABLENAME", Table));
paramList.Add(new SqlParameter("@APPID", Appl));
paramList.Add(new SqlParameter("@BUFFER", Buffer));
................
然后运行报错：
{"The variable name '@TABLENAME' has already been declared. Variable names must be unique within a query batch or stored procedure.\r\nMust declare the table variable \"@TABLENAME\"."}
System.Exception {System.Data.SqlClient.SqlException}
+ e {"Must declare the table variable \"@TABLENAME\"."} System.Exception {System.Data.SqlClient.SqlException}
想起过去也遇到过类似的情况，当时是在order by子句里用过@变量做参数，也是值不进去 - =
后来这么改写之后就没问题了——
sqlBuilder.Append(" INSERT INTO ");
sqlBuilder.AppendFormat(" {0} ", Table);
sqlBuilder.Append(" ([AppID],[Action],[Group],[Buffer],[Operator],[TimeStamp]) ");
sqlBuilder.Append(" VALUES( ");
sqlBuilder.Append(" @APPID, @ACTION, @GROUP, @BUFFER, @USER, @TIME ");
sqlBuilder.Append(" ) ");
虽然问题解决了，可是到现在也不知道原因是什么，难道这种方式只适用于在where子句里使用？囧
另，还见到有人这么写——
string insertSql = string.Format("INSERT INTO [{0}]({1}) VALUES({2})", destTableName, sbFields, sbParams);
http://www.cnblogs.com/upto/articles/1066400.html
自动生成Insert 语句的小工具 http://kb.cnblogs.com/a/1581732/ 这个看起来蛮有意思，哪天有空仔细瞅瞅
StringBuilder动态建表与插数据
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Data.SqlClient;
using System.IO;
using System.Text;
using System.Data;
// 连接字符串，可修改
string ConnectionString = " Data Source=A-FA8619ED2B234\\SQLEXPRESS;Initial Catalog=test;User ID=wxg;Password=test " ;
/// <summary>
/// 判断是否存在表
/// </summary>
/// <param name="table"> 表名 </param>
/// <returns></returns>
public bool HasTable( string table)
{
SqlConnection conn = new SqlConnection(ConnectionString);
string strSql = " select * from dbo.sysobjects where id = object_id(N'[dbo].[ " + table + " ]') and OBJECTPROPERTY(id, N'IsUserTable') = 1 " ;
conn.Open();
SqlCommand cmd = new SqlCommand(strSql, conn);
SqlDataReader dr = cmd.ExecuteReader();
return dr.Read();
}
/// <summary>
/// 动态建表
/// </summary>
/// <param name="ProjectID"> 以项目号作为表名,如123 </param>
/// <param name="PollID"> 问卷编号 </param>
/// <param name="Answer"> 答案列名 </param>
/// <param name="Len"> 全部列的长度数组 </param>
public void CreateTable( string ProjectID, string PollID, string Answer, int [] Len)
{
SqlConnection conn = new SqlConnection(ConnectionString);
// 如果有同名表存在
if (HasTable(ProjectID))
{
MessageBox.Show( " 表 " + ProjectID + " 已经存在 " );
}
else
{
// 创建表
StringBuilder strSql = new StringBuilder();
StringBuilder Column = new StringBuilder();
string Col = "" ;
strSql.Append( " create table " );
strSql.Append( " [ " );
strSql.Append( "" + ProjectID + "" );
strSql.Append( " ] " );
strSql.Append( " ( " );
strSql.Append( " " + PollID + " varchar(50) primary key, " );
for ( int i = 0 ; i < Len.Length; i ++ )
{
int t = i + 1 ;
string An = Answer + t;
Column.Append( "" + An + " varchar( " + Len[i] + " ) , " );
}
if (Column.Length != 0 )
{
Col = Column.ToString().Substring( 0 , Column.Length - 1 );
}
strSql.Append(Col);
strSql.Append( " ); " );
conn.Open();
SqlCommand cmd = new SqlCommand(strSql.ToString(), conn);
cmd.ExecuteNonQuery();
MessageBox.Show( " 创建 " + ProjectID + " 表成功 " );
conn.Close();
}
}
/// <summary>
/// 插入数据到表中
/// </summary>
/// <param name="ProjectID"> 以项目号作为表名,如123 </param>
/// <param name="PollID"> 问卷编号 </param>
/// <param name="Answer"> 答案数组 </param>
public void InsertData( string ProjectID, string PollID, string [] Answer)
{
SqlConnection conn = new SqlConnection(ConnectionString);
StringBuilder strSql = new StringBuilder();
StringBuilder Values = new StringBuilder();
string Va = "" ;
strSql.Append( " insert into " );
strSql.Append( " [ " );
strSql.Append( "" + ProjectID + "" );
strSql.Append( " ] " );
strSql.Append( " values " );
strSql.Append( " ( " );
strSql.Append( " ' " + PollID + " ', " );
for ( int i = 0 ; i < Answer.Length; i ++ )
{
Values.Append( " ' " + Answer[i] + " ' , " );
}
if (Values.Length != 0 )
{
Va = Values.ToString().Substring( 0 , Values.Length - 1 );
}
strSql.Append(Va);
strSql.Append( " ); " );
conn.Open();
SqlCommand cmd = new SqlCommand(strSql.ToString(), conn);
cmd.ExecuteNonQuery();
System.Web.HttpContext.Current.Response.Write( " <script>alert('插入数据到 " + ProjectID + " 表中成功')</script> " );
conn.Close();
}
// **************导出数据到TXT文件
/// <summary>
/// 直接用表名导出数据到同名TXT文件
/// </summary>
/// <param name="ProjectID"> 项目号也是表名,如123 </param>
/// <param name="TXTPATH"> 导出TXT文件目录，格式如 @"G:\"; </param>
public void ToTxt( string ProjectID, string TXTPATH)
{
// 如果表中有数据，则导出数据
if (HasData(ProjectID))
{
DataSet ds = GetData(ProjectID);
ExportToTxt(ds, TXTPATH, ProjectID);
}
else
{
System.Web.HttpContext.Current.Response.Write( " 表中没有数据 " );
}
}
/// <summary>
/// 判断表中是否有数据
/// </summary>
/// <param name="table"> 表名 </param>
public bool HasData( string table)
{
SqlConnection conn = new SqlConnection(ConnectionString);
string strSql = " select * from [ " + table + " ] " ;
conn.Open();
SqlCommand cmd = new SqlCommand(strSql, conn);
SqlDataReader dr = cmd.ExecuteReader();
return dr.Read();
}
/// <summary>
/// 获得数据集Dataset
/// </summary>
/// <param name="table"> 表名 </param>
/// <returns> Dataset </returns>
public DataSet GetData( string table)
{
try
{
string strSql = " select * from [ " + table + " ] " ;
SqlConnection conn = new SqlConnection(ConnectionString);
conn.Open();
SqlDataAdapter da = new SqlDataAdapter(strSql, conn);
DataSet ds = new DataSet();
da.Fill(ds, "" + table + "" );
return ds;
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
/// <summary>
/// 把数据导出到txt文件
/// </summary>
/// <param name="ds"> 数据集Dataset </param>
/// <param name="TXTPATH"> txt文件目录 </param>
/// <param name="ProjectID"> 以项目名作为文件名 </param>
public void ExportToTxt(DataSet ds, string TXTPATH, string ProjectID )
{
string TXTPOSTFIX = " .txt " ;
if (ds.Tables.Count != 0 )
{
// 创建一个.txt文件，文件名用项目名
FileInfo file = new FileInfo( "" + TXTPATH + ProjectID + TXTPOSTFIX + "" );
StreamWriter textFile = null ;
try
{
textFile = file.CreateText();
}
catch
{
System.Web.HttpContext.Current.Response.Write( " 系统找不到指定目录下的文件： " + TXTPATH + ProjectID + TXTPOSTFIX + " " );
return ;
}
// 把Dataset中的数据写入.txt文件中
for ( int totaltable = 0 ; totaltable < ds.Tables.Count; totaltable ++ )
{
// 统计dataset中当前表的行数
int row = ds.Tables[totaltable].Rows.Count;
// 统计dataset中当前表的列数
int column = ds.Tables[totaltable].Columns.Count;
// 用于统计当前表中每列记录中字符数最长的字符串的长度之和
int totalLength = 0 ;
// 把dataset中当前表的数据写入.txt文件中
for ( int i = 0 ; i < row; i ++ )
{
for ( int j = 0 ; j < column; j ++ )
{
textFile.Write(ds.Tables[totaltable].Rows[i][j].ToString());
}
textFile.WriteLine();
}
textFile.WriteLine();
}
// 关闭当前的StreamWriter流
textFile.Close();
System.Web.HttpContext.Current.Response.Write( " 数据文件已保存到 " + " " + file.FullName);
}
else
{
System.Web.HttpContext.Current.Response.Write( " 表中没有数据 " );
}
}
}
取电话号码后10位数字，可是电话号码字符串里可能包含有不定位数的其他字符，所以要先滤掉非数字的字符，只留下数字，然后再截取。
string strPhone = xxxxx;
string tmpPhone = "" ;
Regex reg = new Regex( @" \d+(?:\.\d+)? " );
Match m = reg.Match(strPhone, 0 ); //从第0个开始检查
for (m = reg.Match(strPhone); m.Success; m = m.NextMatch())
{
tmpPhone += m.Value;
}
strPhone = tmpPhone.Substring(tmpPhone.Length - 10 , 10 ); //取电话号码后10位
脏字过滤 http://it-worker.blogbus.com/logs/66665795.html
[转]C#中Trim()、TrimStart()、TrimEnd()的错误认识