>在sqlite3的api函数中有一个sqlite3_exec,用来执行sql语句:
函数原型:
int sqlite3_exec
(
sqlite3* ppDb, /* An open database */
const char sql, / SQL to be evaluated */
int (callback)(void,int,char**,char**), /* Callback function */
void , / 1st argument to callback */
char *errmsg / Error msg written here */
);
第1个参数不再说了,是sqlite3_open函数得到的指针。
第2个参数constchar*sql是一条sql 语句,以\0结尾。
第3个参数sqlite3_callback 是回调,sqlite3每查询到一条结果,都会去调用你提供的这个函数。
第4个参数void*是你所提供的指针,你可以传递任何一个指针参数到这里,这个参数最终会传到回调函数里面,如果不需要传递指针给回调函数,可以填NULL。
第5个参数char** errmsg 是错误信息。注意是指针的指针。sqlite3里面有很多固定的错误信息。执行sqlite3_exec 之后,执行失败时可以查阅这个指针。
回调函数的格式:
int sqlite_callback(
void* pvoid, /* 由 sqlite3_exec() 的第四个参数传递而来 */
int argc, /* 表的列数 */
char** argv, /* 指向查询结果的指针数组, 可以由 sqlite3_column_text() 得到 */
char** col /* 指向表头名的指针数组, 可以由 sqlite3_column_name() 得到 */
);
在所有的回掉函数中,都要加上return 0;否则失去其回调函数的意义。
/*****************************************************
copyright (C), 2014-2015, Lighting Studio. Co., Ltd.
File name:
Author:Jerey_Jobs Version:0.1 Date:
Description:
Funcion List:
*****************************************************/
int create_table(sqlite3 *db)
{
char *errmsg = NULL;
char *sql;
sql = "create table if not exists mytable(id integer primary key,name txt);";
if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
printf("operater failed1 : %s \n",errmsg);
exit(0);
}
}
int insert_record(sqlite3 *db)
{
char *errmsg;
char sql[100];
char name[10];
int id;
int n;
int i;
printf("enter the number \n");
scanf("%d",&n);
for(i = 0; i {
printf("enter the id you want to insert :\n");
scanf("%d",&id);
printf("enter the name you want to insert :\n");
scanf("%s",name);
sprintf(sql,"insert into mytable(id,name) values(%d,'%s');",id,name);
if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
printf("operater failed2 : %s \n",errmsg);
exit(0);
}
}
/* sql = "insert into mytable(id,name) values(NULL,'xie');";
if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
printf("operater failed3 : %s \n",errmsg);
exit(0);
}
sql = "insert into mytable(id,name) values(NULL,'zhen');";
if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
printf("operater failed4 : %s \n",errmsg);
exit(0);
}*/
}
int displaycb(void *para,int n_column,char **column_value,char **column_name)
{
int i;
printf("total column is %d \n",n_column);
for(i = 0;i {
// printf("\t\t %s \t\t %s \n",column_name[i],column_value[i]);
printf("column_name : %s ----> column_value : %s \n",column_name[i],column_value[i]);
}
return 0;
}
int inquire_usecb(sqlite3 *db)
{
char *errmsg;
char *sql;
sql = "select * from mytable;";
if(SQLITE_OK != sqlite3_exec(db,sql,displaycb,NULL,&errmsg))
{
printf("operater failed5 : %s \n",errmsg);
exit(0);
}
}
int delete_record(sqlite3 *db)
{
char *errmsg;
char sql[100];
int id;
printf("enter the id you want to delete\n");
scanf("%d",&id);
sprintf(sql,"delete from mytable where id = %d",id);
if(SQLITE_OK != sqlite3_exec(db,sql,NULL,NULL,&errmsg))
{
printf("operater failed6 :%s \n",errmsg);
exit(0);
}
}
int inquire_nocb(sqlite3 *db)
{
int nrow,ncolumn;
char **azresult;
char *sql;
char *errmsg;
int i;
sql = "select * from mytable;";
if(SQLITE_OK != sqlite3_get_table(db,sql,&azresult,&nrow,&ncolumn,&errmsg))
{
printf("operater failed : %s\n",errmsg);
exit(0);
}
printf("row :%d column :%d\n",nrow,ncolumn);
printf("the result of querying : \n");
for(i = 0;i <(nrow + 1) * ncolumn;i++)
{
printf("%10s",azresult[i]);
if((i + 1) % ncolumn == 0)
{
printf("\n");
}
}
sqlite3_free_table(azresult);
}
int main()
{
sqlite3 *db = NULL;
int ret;
ret = sqlite3_open("mydatabase.db",&db);
if(ret != SQLITE_OK)
{
perror("open error!\n");
exit(0);
}
else
{
printf("you have opened a qulite3 database successfully !\n");
}
create_table(db);
insert_record(db);
inquire_usecb(db);
delete_record(db);
inquire_nocb(db);
sqlite3_close(db);
return 0;
}