<一> 表的检测，创建，删除。

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <sqlite3.h>

bool db_tableExists(sqlite3 *db, const char *tbname)
{
    int nRet;
    const char   *szTail;
    sqlite3_stmt *pvm;
    char sql[1024];
    sprintf(sql, "select count(*) from sqlite_master where type='table' and name='%s'", tbname);

    szTail=0;

    nRet = sqlite3_prepare(db, sql, -1, &pvm, &szTail);

    //printf("nRet=%d SQLITE_OK=%d SQLITE_DONE=%d SQLITE_ROW=%d \n", nRet, SQLITE_OK, SQLITE_DONE,SQLITE_ROW);

    if (nRet==SQLITE_OK)
    {
        nRet=sqlite3_step(pvm);

        //printf("nRet=%d SQLITE_OK=%d SQLITE_DONE=%d SQLITE_ROW=%d \n", nRet, SQLITE_OK, SQLITE_DONE,SQLITE_ROW);

        if (nRet==SQLITE_ROW)
        {
            int nCols = sqlite3_column_count(pvm);
            //printf("nCols:%d\n", nCols);
            if (nCols>=1)
            {
                return sqlite3_column_int(pvm,0)!=0;
            }
        }
    }

    return false;
}

int db_exeDML(sqlite3 *db, const char *sql)
{
    char* szError=0;
    int nRet = sqlite3_exec(db, sql, 0, 0, &szError);
    if (nRet == SQLITE_OK)
    {
        return sqlite3_changes(db);
    }
    return SQLITE_ERROR;
}


int main(int argc, char **argv)
{

    sqlite3 *db=0;
    int  nRet = sqlite3_open("temp.db",&db);

    if (nRet)
    {
        fprintf(stderr,"can't open database: %s\n",sqlite3_errmsg(db));
        sqlite3_close(db);
        exit(1);
    }else{
        printf("open database ok.\n");
    }

    if (!db_tableExists(db,"tmp"))
    {
        printf("create \"tmp\" table\n");
        nRet=db_exeDML(db,"CREATE TABLE tmp( IP TEXT, VER TEXT, UID TEXT, FILE TEXT)");
        printf("nRet=%d\n", nRet);
    }else{
        nRet=db_exeDML(db,"delete from tmp");
        printf("nRet=%d\n", nRet);
    }

    sqlite3_close(db);

    return 0;
}