SQLite3的绑定函数族使用与其注意事项详解

前言

本文给大家展示的代码实际上就是如何利用sqlite3的参数化机制做数据插入，也可以update操作，就看你怎么玩了，这里只列出代码，然后说一些注意事项。

下面的代码，有一个问题，插入后的东西一定是：

insert into "work" values('铪','铪铪铪铪铪',null,null,null,null,'铪铪铪铪铪',null,null,110.0,1.0,108.9,null,null,'铪铪铪铪铪',null,null,null,'铪铪铪铪铪',null,null,null);

看看有问题的代码：

sqlite3_stmt *stmt;
 cstring sql = "insert into work values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
 int rc = sqlite3_prepare_v2(db, sql.getstring(), -1, &stmt, null);

 if(rc != sqlite_ok)
 {
 messagebox("sqlite3_prepare_v2 failed!");
 return;
 }

 count = 0;
 p_wnd = prevwnd;

 while(count++ < id_totalcount)
 {
 cstring dbstr;
 
 p_wnd = cwnd::getnextdlgtabitem(p_wnd, false); 
 if(p_wnd == null)
 {
  return;
 }

 p_wnd->getwindowtext(dbstr);

 do
 {
  if(!dbstr.getlength())
  {
  rc = sqlite3_bind_null(stmt, count);
  break;
  }

  //日期相关
  if( count == id_chudanriqi || 
  count == id_chufariqi || 
  count == id_huankuanriqi || 
  count == id_huoliriqi)
  {
  cdatetimectrl *timectl = (cdatetimectrl *)p_wnd;  
  cstring time = datetimetostring(*timectl);

  rc = sqlite3_bind_text(stmt, count, time.getstring(), time.getlength(), sqlite_static);
  break;
  }
  else
  {
  //金钱相关的处理real类型
  if( count == id_baoxianjine || 
   count == id_yongjinbilv || 
   count == id_jingbaofei || 
   count == id_huankuanjine || 
   count == id_lirunbilv || 
   count == id_lirunjine)
  {
   double tmoney = 0.0;
   int rtn = sscanf_s(dbstr.getstring(), "%lf", &tmoney);

   assert(rtn == 1);

   rc = sqlite3_bind_double(stmt, count, tmoney);
  }
  else
  {
   char *str = (char *)dbstr.getstring();
   int c = strlen(str);
   int c1 = dbstr.getlength();

   rc = sqlite3_bind_text(stmt, count, dbstr.getstring(), -1/*dbstr.getlength()*/, sqlite_static);
  }
  }
 }while(0);

 if(rc != sqlite_ok)
 {
  cstring errstr = sqlite3_errstr(rc);
  messagebox(errstr);

  return;
 }
 }

 rc = sqlite3_step(stmt); 

 if(rc != sqlite_done)
 {
 if(rc == sqlite_error)
 {
  cstring dberr;
  dberr.format("sql insert failed, %s", sqlite3_errmsg(db));

  messagebox(dberr);
 }
 else
 {
  messagebox("sqlite3_step failed!");
 } 
 }

 sqlite3_finalize(stmt);

为什么呢？

因为，sqlite3_bind_text绑定的text，需要在做：

rc = sqlite3_step(stmt); 

的时候统一提交，而上面的代码使用的临时变量，rc = sqlite3_step(stmt);的时候，早就不存在了。因此乱码也是正常的。

修改如下：

sqlite3_stmt *stmt;
 cstring sql = "insert into work values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
 int rc = sqlite3_prepare_v2(db, sql.getstring(), -1, &stmt, null);

 if(rc != sqlite_ok)
 {
 messagebox("sqlite3_prepare_v2 failed!");
 return;
 }

 count = 0;
 p_wnd = prevwnd;

 cstring dbstr[id_totalcount + 1];

 while(count++ < id_totalcount)
 {
 dbstr[count].empty();
 
 p_wnd = cwnd::getnextdlgtabitem(p_wnd, false); 
 if(p_wnd == null)
 {
  return;
 }

 p_wnd->getwindowtext(dbstr[count]);

 do
 {
  if(!dbstr[count].getlength())
  {
  rc = sqlite3_bind_null(stmt, count);
  break;
  }

  //日期相关
  if( count == id_chudanriqi || 
  count == id_chufariqi || 
  count == id_huankuanriqi || 
  count == id_huoliriqi)
  {
  cdatetimectrl *timectl = (cdatetimectrl *)p_wnd;  
  cstring time = datetimetostring(*timectl);

  dbstr[count] = time;

  rc = sqlite3_bind_text(stmt, count, time.getstring(), time.getlength(), sqlite_static);
  }
  else
  {
  //金钱相关的处理real类型
  if( count == id_baoxianjine || 
   count == id_yongjinbilv || 
   count == id_jingbaofei || 
   count == id_huankuanjine || 
   count == id_lirunbilv || 
   count == id_lirunjine)
  {
   double tmoney = 0.0;
   int rtn = sscanf_s(dbstr[count].getstring(), "%lf", &tmoney);

   assert(rtn == 1);

   rc = sqlite3_bind_double(stmt, count, tmoney);
  }
  else
  {
   rc = sqlite3_bind_text(stmt, count, dbstr[count].getstring(), dbstr[count].getlength(), sqlite_static);
  }
  }
 }while(0);

 if(rc != sqlite_ok)
 {
  cstring errstr = sqlite3_errstr(rc);
  messagebox(errstr);

  return;
 }
 }

 rc = sqlite3_step(stmt); 

 if(rc != sqlite_done)
 {
 if(rc == sqlite_error)
 {
  cstring dberr;
  dberr.format("sql insert failed, %s", sqlite3_errmsg(db));

  messagebox(dberr);
 }
 else
 {
  messagebox("sqlite3_step failed!");
 } 
 }

 sqlite3_finalize(stmt);

附上数据库创建的sql语法：

sqlite> .dump work
pragma foreign_keys=off;
begin transaction;
create table work (baodanhao text unique primary key , chudanriqi text,qudao text,lianxiren text,xiaoshou text,beibaorenxingming text,chufar
iqi text,baoxianpinpai text,baoxianjihua text,baoxianjine real,yongjinbilv real,jingbaofei real,huankuanfangshi text,haikuanjine real,huanku
anriqi text,shifouquane text,lirunbilv real,lirunjine real,huoliriqi text,fapiaojisong text,shifubaoxiangongsi text,beizhu text);

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对的支持。