Question

我编写了以下代码，将一些记录从另一个数据库的表中插入到表中但我无法做到，即使在执行sql语句后，它也显示表中没有记录。

public int copy_to_all_source_table(String dbpath,String backpath)
{
    SQLiteDatabase db1 = this.getWritableDatabase();

    //Opening App database(i.e. dbpath) and attaching it as "OLD" 
    db1.openDatabase(dbpath, null, SQLiteDatabase.OPEN_READWRITE);
    String attach_old="ATTACH '"+ dbpath +"' AS OLD";
    db1.execSQL(attach_old);

    //Opening New File which is Student.db(i.e. dbpath) and attaching it as "NEW"        
    db1.openDatabase(backpath, null, SQLiteDatabase.OPEN_READWRITE);
    String attach_new="ATTACH '"+ backpath +"' AS NEW";
    db1.execSQL(attach_new);

    // Getting count of records in table of "NEW" 
    String new_query =" SELECT * FROM 'NEW'.'"+ TABLE_CONTACTS +"'";
    Cursor new_data = db1.rawQuery(new_query, null);          
    Integer new_count= new_data.getCount();


    //INSERTING ALL RECORDS FROM TABLE OF NEW TO TABLE OF OLD
    String insert_query ="INSERT INTO 'OLD'.'"+ TABLE_CONTACTS +"' SELECT * FROM 'NEW'.'"+ TABLE_CONTACTS +"'";
    Cursor success_insert = db1.rawQuery(insert_query, null);

    // Getting count of records in table of "NEW"
    String after_insert_old_query =" SELECT * FROM 'OLD'.'"+ TABLE_CONTACTS +"'";
    Cursor old_data = db1.rawQuery(after_insert_old_query, null);             
    Integer old_count= old_data.getCount();
}

结果：

new_count = 11
old_count = 0

所以，没有插入任何记录。

Answer 1

您正在使用rawQuery()执行INSERT 命令。哪个永远不会工作 请使用execSQL()，而不是

此外，最后一条评论具有误导性，因为它表示您希望从新表中计算，但您从 OLD 表中计算。

并且，请摆脱字符串分隔符（'）。
即：

此

String new_query =" SELECT * FROM 'NEW'.'"+ TABLE_CONTACTS +"'";

应该是

String new_query = "SELECT * FROM NEW." +  TABLE_CONTACTS;

SQLite插入查询多个数据库

1 个答案: