iphone - SQLite3 - 乱序调用的库例程

Question

当为 SQLite3 db-select 查询运行以下准备语句时，我收到 SQLLite 错误 21“库例程调用顺序错误”:

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)]);

我做错了什么？

Answer 1

经过进一步调查，我发现了我的错误。我应该在运行准备语句之前先打开数据库。

代码应该是这样的:

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)]);
...