ios Sqlite 连接

Question

我的问题是我正在尝试将我的数据库连接到 sqlite。它总是出现错误“找不到表”..我现在该怎么办..请帮忙这是我的 opendatabaseconnectivity 代码....

BOOL openDatabaseResult = sqlite3_open([databasePath UTF8String], &sqlite3Database);
    if(openDatabaseResult == SQLITE_OK) {
        // Declare a sqlite3_stmt object in which will be stored the query after having been compiled into a SQLite statement.
        sqlite3_stmt *compiledStatement;

        // Load all data from database to memory.
        BOOL prepareStatementResult = sqlite3_prepare_v2(sqlite3Database, query, -1, &compiledStatement, NULL);
        if(prepareStatementResult == SQLITE_OK) {
            // Check if the query is non-executable.
            if (!queryExecutable){
                // In this case data must be loaded from the database.

                // Declare an array to keep the data for each fetched row.
                NSMutableArray *arrDataRow;

                // Loop through the results and add them to the results array row by row.
                while(sqlite3_step(compiledStatement) == SQLITE_ROW) {
                    // Initialize the mutable array that will contain the data of a fetched row.
                    arrDataRow = [[NSMutableArray alloc] init];

                    // Get the total number of columns.
                    int totalColumns = sqlite3_column_count(compiledStatement);

                    // Go through all columns and fetch each column data.
                    for (int i=0; i<totalColumns; i++){
                        // Convert the column data to text (characters).
                        char *dbDataAsChars = (char *)sqlite3_column_text(compiledStatement, i);

                        // If there are contents in the currenct column (field) then add them to the current row array.
                        if (dbDataAsChars != NULL) {
                            // Convert the characters to string.
                            [arrDataRow addObject:[NSString  stringWithUTF8String:dbDataAsChars]];
                        }

                        // Keep the current column name.
                        if (self.arrColumnNames.count != totalColumns) {
                            dbDataAsChars = (char *)sqlite3_column_name(compiledStatement, i);
                            [self.arrColumnNames addObject:[NSString stringWithUTF8String:dbDataAsChars]];
                        }
                    }

                    // Store each fetched data row in the results array, but first check if there is actually data.
                    if (arrDataRow.count > 0) {
                        [self.arrResults addObject:arrDataRow];
                    }
                }
            }
            else {
                // This is the case of an executable query (insert, update, ...).

                // Execute the query.
                BOOL executeQueryResults = sqlite3_step(compiledStatement);
                if (executeQueryResults == true) {
                    // Keep the affected rows.
                    self.affectedRows = sqlite3_changes(sqlite3Database);

                    // Keep the last inserted row ID.
                    self.lastInsertedRowID = sqlite3_last_insert_rowid(sqlite3Database);
                }
                else {
                    // If could not execute the query show the error message on the debugger.
                    NSLog(@"DB Error: %s", sqlite3_errmsg(sqlite3Database));
                }
            }
        }
        else {
            // In the database cannot be opened then show the error message on the debugger.
            NSLog(@"%s", sqlite3_errmsg(sqlite3Database));
        }

        // Release the compiled statement from memory.
        sqlite3_finalize(compiledStatement);

    }

    // Close the database.
    sqlite3_close(sqlite3Database);
}

Answer 1

在访问你的数据库之前，你是否将它复制到文档目录中？

像这样:

static sqlite3 *database = nil;

+ (void)openDatabase
{
    [self copyDatabaseIfNeeded];
    (sqlite3_open([[self getDBPath] UTF8String],&database));
}

+ (NSString *)getDBPath
{
    NSArray *paths =         NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *documentsDir = [paths objectAtIndex:0];
    NSLog(@"%@",documentsDir);
    return [documentsDir stringByAppendingPathComponent:@"databaseName.sqlite"];
}

+ (void)copyDatabaseIfNeeded
{
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSString *dbPath = [self getDBPath];
    BOOL success = [fileManager fileExistsAtPath:dbPath];

    NSLog(@"dbpath=%@",dbPath);
    if(!success)
    {
        NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"databaseName.sqlite"];
        success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];

        if (!success)
            NSAssert1(0, @"Failed to create writable database file with message \"%@\".", [error localizedDescription]);
    }
} 

在使用前还要检查您要访问的表是否已在数据库中创建。