FMDB 字典查询

Question

我需要运行一个查询，看起来像是

INSERT INTO Appointments (field1, field2, field3, ..., field30) VALUES (value1, value2, value3, ..., value30)

我的约会存储在字典中，并且希望循环遍历该字典以使键等于字段并且值等于值。

我正在尝试使用 executeUpdate:... withParameterDictionary:... 但如果我不知道字段名称，则无法弄清楚如何使其适用于多个字段。字段名称是通过 JSON 发送的，我不想手动输入 30 个字段，而是想循环遍历字典并以这种方式获取它们。

我什至尝试过

NSMutableArray *keys = nil;
 NSMutableArray *values = nil;

        for (NSDictionary *dict in [json objectForKey:@"data"]) {
            keys = [NSMutableArray array];
            values = [NSMutableArray array];
            for (id key in dict) {
                [keys addObject:key];
                [values addObject:[NSString stringWithFormat:@":%@", key]];
            }
            NSString *keyString = [keys componentsJoinedByString:@","];
            NSString *valueString = [values componentsJoinedByString:@","];
            [[dataObj db] executeUpdate:@"DELETE FROM Appointments"];
            NSLog(@"INSERT INTO Appointments (%@) VALUES (%@)", keyString, valueString);
            [[dataObj db] executeUpdate:@"INSERT INTO Appointments (?) VALUES (?)", keyString, valueString];

        }

上面的代码打印 NSLog 查询应该如何显示，但没有任何内容被插入到数据库中。我知道这一点是因为我在查询运行后打开模拟器数据库文件，但它仍然是空白的。

如何使上述代码正常工作，或者如何使 executeQuery:... withParameterDictionary:... 处理多个名称。

Answer 1

我进行了一些快速测试，这对我有用：

NSDictionary* dict = [NSDictionary dictionaryWithObjectsAndKeys:@"AAAA44", @"a", @"BBBB44", @"b", @"CCCC44", @"c", nil];
NSMutableArray* cols = [[NSMutableArray alloc] init];
NSMutableArray* vals = [[NSMutableArray alloc] init];
for (id key in dict) {
    [cols addObject:key];
    [vals addObject:[dict objectForKey:key]];
}
NSMutableArray* newCols = [[NSMutableArray alloc] init];
NSMutableArray* newVals = [[NSMutableArray alloc] init];
for (int i = 0; i<[cols count]; i++) {
    [newCols addObject:[NSString stringWithFormat:@"'%@'", [cols objectAtIndex:i]]];
    [newVals addObject:[NSString stringWithFormat:@"'%@'", [vals objectAtIndex:i]]];
}
NSString* sql = [NSString stringWithFormat:@"insert into test (%@) values (%@)", [newCols componentsJoinedByString:@", "], [newVals componentsJoinedByString:@", "]];
NSLog(@"%@", sql);
BOOL updateSuccess = [db executeUpdate:sql];

技巧是将 ' 添加到数组中的数据中。

Answer 2

NSDictionary *argsDict 
    = [NSDictionary dictionaryWithObjectsAndKeys:@"My Name", 
       @"name", nil];

[db executeUpdate:@"INSERT INTO myTable (name) VALUES (:name)"
    withParameterDictionary:argsDict];

Answer 3

这是我刚刚编写的一些示例代码，用于在插入时支持可选值。只是简单测试过，但我认为它有效。

    NSMutableDictionary* fieldsandvalues = [NSMutableDictionary dictionary];
    fieldsandvalues[@"word"] = userphrase.word;
    fieldsandvalues[@"translation"] = userphrase.translation;
    if (userphrase.samplesentence.length > 0) {
        fieldsandvalues[@"samplesentence"] = userphrase.samplesentence;
    }
    if (userphrase.notes.length > 0) {
        fieldsandvalues[@"notes"] = userphrase.notes;
    }

    NSMutableArray* keyswithcolon = [NSMutableArray array];
    for (NSString* key in fieldsandvalues.allKeys) {
        [keyswithcolon addObject:[NSString stringWithFormat:@":%@", key]];
    }

    NSString* sql = [NSString stringWithFormat:@"INSERT INTO userphrase (%@) VALUES (%@)", [fieldsandvalues.allKeys componentsJoinedByString:@","], [keyswithcolon componentsJoinedByString:@","]];
//  DLog(@"sql: %@", sql);
    if (![self.db executeUpdate:sql withParameterDictionary:fieldsandvalues]) {
        NSAssert(NO, @"Failed inserting userphrase into database! Last error: %@ - %@", self.db.lastError, self.db.lastErrorMessage);
        return nil;
    }