插入查询不起作用（FMDB）

Question

这是我用来将记录插入到 sqlite 表中的代码

FMDatabase *dataBase = [self openDatabase];
    [dataBase open];
    if ([dataBase open] != YES) {
        NSLog(@"DB Error %d: %@", [dataBase lastErrorCode], [dataBase lastErrorMessage]);
    //VERY IMPORTANT
    }

    BOOL success= [dataBase executeUpdate:@"Insert into CrewUnits (pkCrewUnits,fkUnits,fkAgencyVehicles,fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, PrimaryUnit) values (?, ?, ?, ?, ?, ?);", pkCrewUnits, fkUnits, fkAgencyVehicle, fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, [NSNumber numberWithInt:1]];
    NSLog(success ?@"YES" :@"NO");
     NSLog(@"Error %d: %@", [dataBase lastErrorCode], [dataBase lastErrorMessage]);
   FMResultSet*resultSet= [dataBase executeQuery:@"select * from CrewUnits"];
    NSLog(@"ResultSet : %@", [resultSet resultDictionary]);

    [dataBase close];

数据库路径

- (FMDatabase *)openDatabase
{

    NSLog(@"Open Database");
    NSString *documents_dir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *db_path = [documents_dir stringByAppendingPathComponent:[NSString stringWithFormat:@"HPSix_05BD.db"]];    // DatabasePath
    FMDatabase *db = [FMDatabase databaseWithPath:db_path];
    if (![db open])
        NSLog(@"Failed to open database!!!!!");
    return db;
}

我使用相同的逻辑从适合我的表中获取数据。但我无法插入记录。我不知道我在这里做错了什么。

Answer 1

两个问题：

1. 您拨打了三遍open。一次在openDatabase 中，两次在调用它的代码中。

   所以，如果可以，让您的 open 例程打开数据库，但如果不能，则返回 nil：

   - (FMDatabase *)openDatabase
   {
       NSLog(@"Open Database");
       NSString *documents_dir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
       NSString *db_path = [documents_dir stringByAppendingPathComponent:[NSString stringWithFormat:@"HPSix_05BD.db"]];    // DatabasePath
       FMDatabase *db = [FMDatabase databaseWithPath:db_path];
       if (![db open]) {
           NSLog(@"Failed to open database!!!!!");
           return nil;
       }
       return db;
   }
   

   然后检查结果：

   FMDatabase *dataBase = [self openDatabase];
   if (!dataBase) {
       // quit; note, no point in checking error message as it only returns meaningful messages if you have an open database
   }
   

2. 调用executeQuery后，必须调用next。

   FMResultSet *resultSet = [dataBase executeQuery:@"select * from CrewUnits"];
   if ([resultSet next]) {
       NSLog(@"ResultSet : %@", [resultSet resultDictionary]);
   } else {
       NSLog(@"No data found");
   }
   

Answer 2

我想我看到了问题所在。您在运行 SELECT 查询后提交。

您必须在 UPDATE 查询之后立即提交。当您像现在选择时那样执行此操作时，UPDATE 查询尚未提交，因此不会返回。

[dataBase beginTransaction];
BOOL success= [dataBase executeUpdate:@"Insert into CrewUnits (pkCrewUnits,fkUnits,fkAgencyVehicles,fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, PrimaryUnit) values (?, ?, ?, ?, ?, ?);", pkCrewUnits, fkUnits, fkAgencyVehicle, fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, [NSNumber numberWithInt:1]];
[dataBase commit]; // commit the query
NSLog(success ?@"YES" :@"NO");
NSLog(@"Error %d: %@", [dataBase lastErrorCode], [dataBase lastErrorMessage]);
// now at this point the transaction has been committed and can be selected
FMResultSet*resultSet= [dataBase executeQuery:@"select * from CrewUnits"];
NSLog(@"ResultSet : %@", [resultSet resultDictionary]);

还有according to FMDB docs:

参数必须以冒号开头。 SQLite 本身支持其他 字符，但在内部字典键带有前缀 冒号，不要在字典键中包含冒号。

因此这行代码必须重写为：

BOOL success= [dataBase executeUpdate:@"Insert into CrewUnits (pkCrewUnits,fkUnits,fkAgencyVehicles,fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, PrimaryUnit) values (:pkCrewUnits,:fkUnits,:fkAgencyVehicles,:fkLookupCodes_PrimaryRole, :fkLookupCodes_LevelOfCare, :PrimaryUnit);", pkCrewUnits, fkUnits, fkAgencyVehicle, fkLookupCodes_PrimaryRole, fkLookupCodes_LevelOfCare, [NSNumber numberWithInt:1]];

最后根据您使用next 循环结果的文档：

while ([resultSet next]) {
    //retrieve values for each record
}