SQLite 查询给出不同的结果

Question

我正在用 C 语言开发一个小型应用程序，我想使用 SQLite 对数据库执行一些查询。问题是我的行为很奇怪。

如果我在 Firefox 插件“SQLite Manager”上的同一个数据库上运行相同的查询，我会得到预期的结果，但是如果我通过程序中的 C 接口(interface)运行它，我会得到结果元组的错误顺序。

可以查到数据库here (CSV 或 SQLite 格式)，而有问题的查询是这个:

SELECT name, slot, id, species_id 
FROM type_names T, pokemon_types PT, pokemon P 
WHERE T.type_id = PT.type_id 
AND P.id = PT.pokemon_id AND T.local_language_id = 9 
AND P.identifier LIKE '%char%' 
ORDER BY P.species_id;

在 Firefox 上我得到了预期的结果:

+--------+------+-------+------------+|  name  | slot |  id   | species_id |+--------+------+-------+------------+| Fire   |    1 |     4 |          4 || Fire   |    1 |     5 |          5 || Fire   |    1 |     6 |          6 || Flying |    2 |     6 |          6 || Fire   |    1 | 10034 |          6 || Dragon |    2 | 10034 |          6 || Fire   |    1 | 10035 |          6 || Flying |    2 | 10035 |          6 || Fire   |    1 |   390 |        390 |+--------+------+-------+------------+

while in C I get this:

+--------+------+-------+------------+|  name  | slot |  id   | species_id |+--------+------+-------+------------+| Fire   |    1 |     4 |          4 || Fire   |    1 |     5 |          5 || Flying |    2 |     6 |          6 || Flying |    2 | 10035 |          6 || Fire   |    1 |     6 |          6 || Fire   |    1 | 10034 |          6 || Fire   |    1 | 10035 |          6 || Dragon |    2 | 10034 |          6 || Fire   |    1 |   390 |        390 |+--------+------+-------+------------+

I also tried with some simple code that only access the database with that query and I always get the same problem, here is the code:

#include <stdio.h>
#include <sqlite3.h>

// argument 1 is path to db, argument 2 is query

static int callback(void *NotUsed, int argc, char **argv, char **azColName){

    int i;
    for(i=0; i<argc; i++){
        printf("%s\t", argv[i] ? argv[i] : "NULL");
    }
    printf("\n");
    return 0;
}

int main(int argc, char **argv){
    sqlite3 *db;
    char *zErrMsg = 0;
    int rc;

    if( argc!=3 ){
        fprintf(stderr, "Usage: %s DATABASE SQL-STATEMENT\n", argv[0]);
        return(1);
    }
    rc = sqlite3_open(argv[1], &db);
    if( rc ){
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
        sqlite3_close(db);
        return(1);
    }
    rc = sqlite3_exec(db, argv[2], callback, 0, &zErrMsg);
    if( rc!=SQLITE_OK ){
        fprintf(stderr, "SQL error: %s\n", zErrMsg);
        sqlite3_free(zErrMsg);
    }
    sqlite3_close(db);
    return 0;
}

Answer 1

看起来你在期待:

SELECT name, slot, id, species_id 
FROM type_names T, pokemon_types PT, pokemon P 
WHERE T.type_id = PT.type_id 
AND P.id = PT.pokemon_id 
AND T.local_language_id = 9 
AND P.identifier LIKE '%char%' ORDER BY P.species_id, id, slot ASC;

进一步限定您的 ORDER BY 以便能够准确复制结果。