c ++：使用SQLite创建数据库插入&更新 [英] c++ : Create database using SQLite for Insert & update

问题描述

我试图使用sqlite3 lib创建一个数据库在c + +。我得到错误 sqlite3_prepare_v2'

没有在此范围中声明，如logcat所示。

日志文件

  .. \src\Test.cpp：在函数'int main（int，const char **）'中：
 ..\src\Test.cpp：21：85：错误：'sqlite3_prepare_v2'未在此范围中声明
。 .\src\Test.cpp：30：13：错误：变量'sqlite3在'有初始化器但不完整的类型
 ..\src\Test.cpp：30：30：错误：无效使用不完整类型'sqlite3 {aka struct sqlite3}'
 .. \src\ / sqlite3.h：73：16：错误：正向声明'sqlite3 {aka struct sqlite3}'
 
  
 #include< iostream> 
 using namespace std; 
 #includesqlite3.h
 
 int main（int argc，const char * argv []）{
 
 sqlite3 * db; 
 sqlite3_open（test.db，& db）; 
 
 string createQuery =CREATE TABLE IF NOT EXISTS items（busid INTEGER PRIMARY KEY，ipaddr TEXT，time TEXT NOT NULL DEFAULT（NOW（）））;; 
 sqlite3_stmt * createStmt; 
 cout<< 创建表语句< endl; 
 sqlite3_prepare_v2（db，createQuery.c_str（），createQuery.size（），& createStmt，NULL）; 
 cout<< 步进表语句< endl; 
 if（sqlite3_step（createStmt）！= SQLITE_DONE）cout<< 没有创建表！ << endl; 
 
 string insertQuery =INSERT INTO items（time，ipaddr）VALUES（'test'，'192.168.1.1'）;; // WORKS！ 
 
 
 sqlite3_stmt * insertStmt; 
 cout<< 创建插入语句< endl; 
 sqlite3_prepare（db，insertQuery.c_str（），insertQuery.size（），& insertStmt，NULL）; 
 cout<< Stepping Insert Statement< endl; 
 if（sqlite3_step（insertStmt）！= SQLITE_DONE）cout<< 没有插入项目！ << endl; 
 
 cout<< 成功！ << endl; 
 
 return 0; 
} 
  
请帮助我。感谢..... 
解决方案
 
  #include< sqlite3.h> 
  
应包含sqlite3_prepare_v2和struct sqlite3。确保你包含正确的sqlite3.h文件。
 
 
 
在sqlite3_prepare_v2中，第三个参数可以是（你应该是这样）-1，所以sql是
 
 
 
使用sqlite 3.7.11工作裸机示例：
  #include< sqlite3.h> 
 int test（）
 {
 sqlite3 * pDb = NULL; 
 sqlite3_stmt * query = NULL; 
 int ret = 0; 
 do //避免嵌套if的
 {
 //初始化引擎
 if（SQLITE_OK！=（ret = sqlite3_initialize（）））
 {
 printf （无法初始化库：％d \\\
，ret）; 
 break; 
} 
 //打开到DB的连接
 if（SQLITE_OK！=（ret = sqlite3_open_v2（test.db，& pDb，SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE，NULL）））
 {
 printf（无法打开conn：％d \\\
，ret）; 
 break; 
} 
 //准备语句
 if（SQLITE_OK！=（ret = sqlite3_prepare_v2（pDb，SELECT 2012，-1，& query，NULL）））
 {
 printf（无法准备插入：％d，％s\\\
，ret，sqlite3_errmsg（pDb））; 
 break; 
} 
 //到第一行数据
 if（SQLITE_ROW！=（ret = sqlite3_step（query）））//参见文档，这可以返回更多的值as success 
 {
 printf（步骤失败：％d，％s\\\
，ret，sqlite3_errmsg（pDb））; 
 break; 
} 
 // ...并打印列0的值（expect 2012 here）
 printf（sqlite：％s，sqlite3_column_text（query，0） 
 
} while（假）; 
 // cleanup 
 if（NULL！= query）sqlite3_finalize（query）; 
 if（NULL！= pDb）sqlite3_close（pDb）; 
 sqlite3_shutdown（）; 
 return ret; 
} 
  
希望这有助于
 
I am trying to create a database in c++ using sqlite3 lib.. I am getting error sqlite3_prepare_v2'

 was not declared in this scope as shown in logcat.

log file
..\src\Test.cpp: In function 'int main(int, const char**)':
..\src\Test.cpp:21:85: error: 'sqlite3_prepare_v2' was not declared in this scope
..\src\Test.cpp:30:13: error: variable 'sqlite3 in' has initializer but incomplete type
..\src\Test.cpp:30:30: error: invalid use of incomplete type 'sqlite3 {aka struct sqlite3}'
..\src\/sqlite3.h:73:16: error: forward declaration of 'sqlite3 {aka struct sqlite3}'
Here is my code
#include <iostream>
using namespace std;
 #include "sqlite3.h"

 int main (int argc, const char * argv[]) {

sqlite3 *db;
sqlite3_open("test.db", & db);

   string createQuery = "CREATE TABLE IF NOT EXISTS items (busid INTEGER PRIMARY KEY, ipaddr TEXT,    time TEXT NOT NULL DEFAULT (NOW()));";
   sqlite3_stmt *createStmt;
  cout << "Creating Table Statement" << endl;
  sqlite3_prepare_v2(db, createQuery.c_str(), createQuery.size(), &createStmt, NULL);
   cout << "Stepping Table Statement" << endl;
   if (sqlite3_step(createStmt) != SQLITE_DONE) cout << "Didn't Create Table!" << endl;

   string insertQuery = "INSERT INTO items (time, ipaddr) VALUES ('test', '192.168.1.1');"; // WORKS!


   sqlite3_stmt *insertStmt;
   cout << "Creating Insert Statement" << endl;
   sqlite3_prepare(db, insertQuery.c_str(), insertQuery.size(), &insertStmt, NULL);
   cout << "Stepping Insert Statement" << endl;
   if (sqlite3_step(insertStmt) != SQLITE_DONE) cout << "Didn't Insert Item!" << endl;

cout << "Success!" << endl;

 return 0;
}
please help me out. thanks.....
解决方案
 #include <sqlite3.h>
should contain sqlite3_prepare_v2 and struct sqlite3. Make sure you're including the right sqlite3.h file.

Also in sqlite3_prepare_v2 the 3rd arg can be (and should be in your case) -1 so the sql is read to the first null terminator.

Working bare-metal sample using sqlite 3.7.11:
#include <sqlite3.h>
int test()
{
    sqlite3* pDb = NULL;
    sqlite3_stmt* query = NULL;
    int ret = 0;
    do // avoid nested if's
    {
        // initialize engine
        if (SQLITE_OK != (ret = sqlite3_initialize()))
        {
            printf("Failed to initialize library: %d\n", ret);
            break;
        }
        // open connection to a DB
        if (SQLITE_OK != (ret = sqlite3_open_v2("test.db", &pDb, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL)))
        {
            printf("Failed to open conn: %d\n", ret);
            break;
        }
        // prepare the statement
        if (SQLITE_OK != (ret = sqlite3_prepare_v2(pDb, "SELECT 2012", -1, &query, NULL)))
        {
            printf("Failed to prepare insert: %d, %s\n", ret, sqlite3_errmsg(pDb));
            break;
        }
        // step to 1st row of data
        if (SQLITE_ROW != (ret = sqlite3_step(query))) // see documentation, this can return more values as success
        {
            printf("Failed to step: %d, %s\n", ret, sqlite3_errmsg(pDb));
            break;
        }
        // ... and print the value of column 0 (expect 2012 here)
        printf("Value from sqlite: %s", sqlite3_column_text(query, 0));     

    } while (false);
    // cleanup
    if (NULL != query) sqlite3_finalize(query);
    if (NULL != pDb) sqlite3_close(pDb);
    sqlite3_shutdown();
    return ret;
}
Hope this helps

                        
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