sqlite3的 - 圖書館例行的呼叫順序

Question

運行時，以下爲sqlite3的DB-selecct查詢，我得到一個SQLLite錯誤「叫了序列的圖書館例行」 21準備聲明：

sqlite3    *lDb; 
sqlite3_stmt   *lStmt; 
NSNumberFormatter  *lNbrFmt = [[[NSNumberFormatter alloc] init] autorelease]; 

// Define SQL statement 
NSString *lSql = @"SELECT section, language, title, description" 
@"      selector-x-pos, selector-y-pos, gps-x-pos, gps-y-pos" 
@"     FROM sections" 
@"    ORDER BY section ASC"; 

lSqlResult = sqlite3_prepare_v2(lDb, [lSql UTF8String], -1, &lStmt, NULL); 
NSLog(@"%@", [NSString stringWithUTF8String:sqlite3_errmsg(lDb)]); 

什麼時我做錯了？

Answer 1

Uopon進一步調查我發現我的錯誤。在運行準備語句之前，我應該先打開db。

的代碼應該是這樣的：

sqlite3    *lDb; 
sqlite3_stmt   *lStmt; 
NSNumberFormatter  *lNbrFmt = [[[NSNumberFormatter alloc] init] autorelease]; 

// Define SQL statement 
NSString *lSql = @"SELECT section, language, title, description" 
@"      selector-x-pos, selector-y-pos, gps-x-pos, gps-y-pos" 
@"     FROM sections" 
@"    ORDER BY section ASC"; 

if(sqlite3_open([[fileMethods databasePath] UTF8String], &lDb) == SQLITE_OK) { 
    lSqlResult = sqlite3_prepare_v2(lDb, [lSql UTF8String], -1, &lStmt, NULL); 
    NSLog(@"%@", [NSString stringWithUTF8String:sqlite3_errmsg(lDb)]); 
...