尝试返回 iPhone 上的 SQLite 中是否存在记录,但我不断收到“未知错误”。
selectStmtstatic sqlite3_stmt *selectStmt = nil;
在这里使用if(selectStmt) sqlite3_finalize(selectStmt);
,只有在应用程序终止时才会执行。此功能适用于删除语句和插入语句,所以我猜下面的逻辑有问题?
- (BOOL) doesBookExist {
if(selectStmt == nil) {
const char *sql = "select count(*) from books where isbn = ?";
if(sqlite3_prepare_v2(database, sql, -1, &selectStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating select statement. '%s'", sqlite3_errmsg(database));
}
//When binding parameters, index starts from 1 and not zero.
int count = sqlite3_bind_text(selectStmt, 1, [isbn UTF8String], -1, SQLITE_TRANSIENT);
if (SQLITE_DONE != sqlite3_step(selectStmt))
NSAssert1(0, @"Error while selecting. '%s'", sqlite3_errmsg(database));
sqlite3_reset(selectStmt);
return (count > 0);
}