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iPhone上锁定的sqlite文件

sqlite3 iphone

1

Glenn · 技术社区 · 14 年前

到目前为止,我所有的数据库访问权限都在读取,但现在我需要更新(在这个插入之后)

我在应用程序目录中有一个包含“显示”的数据库(只读),这对我来说没问题(我不想把它复制到文档文件夹中,因为它很大,我不需要更改其中的内容。

但我希望用户选择一些节目作为自己的最爱。因此,我在documents文件夹中创建了一个带有“favorite_show”表的数据库。它包含4个字段: ID(主键) 显示ID 是你的最爱备注(目前尚未使用)

用户可以切换一次“最喜爱”状态,之后,我在尝试更新时出错:

sqlite_busy 5/*数据库文件被锁定*/

这是我的代码:

if (sqlite3_open([databasePath UTF8String],&database) == SQLITE_OK){
    sqlStatement = "select * from favorite_shows WHERE (show_id = ?)";
    if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
        sqlite3_bind_int(compiledStatement, 1, self.ID);
        // search for a show
        if(sqlite3_step(compiledStatement) == SQLITE_ROW) {
            // if we can find one, toggle the status
            favID       = sqlite3_column_int(compiledStatement, 0); // we need the primary key to update it
            isFav       = (sqlite3_column_int(compiledStatement, 2) == 1); // let's store the favorite status

            sqlStatement = "update favorite_shows SET is_favorite = ? WHERE (ID = ?)";
            if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) {
                sqlite3_bind_int(compiledStatement, 1, !isFav );                
                sqlite3_bind_int(compiledStatement, 2, favID);
                int error = sqlite3_step(compiledStatement);
                if (SQLITE_DONE != error) {
                    NSLog(@"error while updating favorite status");
                }
            }   
        }
        //else :  no records found indicating that this show hasn't been a favorite yet, so insert one as favorite

sqlite3_finalize(compiledStatement);        
sqlite3_close(database);
}

它第二次被锁定的原因是什么?除此之外,还有其他指示吗? sqlite3_Finalize(compiledStatement);
sqlite3_close(数据库); 关闭一切?

1 回复 | 直到 14 年前

1

8

falconcreek 14 年前

编辑:

忙碌是重新使用的结果 compiledStatement 不删除以前编译的语句。您需要使用Finalize和Close函数适当地释放资源。请参阅此处的文档。 http://sqlite.org/c3ref/stmt.html

const char * select = "select * from favorite_shows WHERE (show_id = ?)";
const char * update = "update favorite_shows SET is_favorite = ? WHERE (ID = ?)";

sqlite3_stmt *selectStmt;
sqlite3_stmt *updateStmt;


if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {
    if(sqlite3_prepare_v2(database, select, -1, &selectStmt, NULL) == SQLITE_OK) {
        sqlite3_bind_int(selectStmt, 1, self.ID);
        // search for a show
        if(sqlite3_step(selectStmt) == SQLITE_ROW) {
            // if we can find one, toggle the status
            favID       = sqlite3_column_int(selectStmt, 0); // we need the primary key to update it
            isFav       = (sqlite3_column_int(selectStmt, 2) == 1) ? 0 : 1; // Flip is_favorite value
            sqlite3_finalize(selectStmt); // Delete the statement OR create a new one

            if(sqlite3_prepare_v2(database, update, -1, &updateStmt, NULL) == SQLITE_OK) {
                sqlite3_bind_int(updateStmt, 1, isFav );                
                sqlite3_bind_int(updateStmt, 2, favID);
                int error = sqlite3_step(updateStmt);
                if (SQLITE_DONE != error) {
                    NSLog(@"error while updating favorite status");
                } else {
                sqlite3_finalize(updateStmt);
                }
            }
    } //else :  no records found indicating that this show hasn't been a favorite yet, so insert one as favorite
 }
    sqlite3_close(database);
}