如何在android中传递多个值进行动态查询？

Question

在我的项目中，我必须选择多个值并将其传递给查询。例如，page1包含复选框。我正在将选中的复选框id存储到一个数组中。我正在对该数组进行混洗，并随机获取这些值。现在，我需要将这些随机值传递给一个查询。在数据库中使用IN操作符，我可以静态地传递这些值，但是如何将这些值动态地传递给查询呢？

对于ex：(静态传值)

SELECT * FROM Persons WHERE person_id IN ('21','22')

在上面的查询中，id的21和22是预先知道的，所以我们是静态传递的，但我想发送动态查询的值。

Page1:
public static ArrayList<String> chksublist = new ArrayList<String>();

Page2:
 Collections.shuffle(chksublist );
SELECT * FROM Persons WHERE person_id IN ('21','22')
In the above line I want to send the random values which are in chksublist array.

Answer 1

String query = "SELECT * FROM Persons WHERE person_id IN (" + TextUtils.join(",", chksublist) + ")";

但是，在将chksublist发送到您的SQL查询之前，对它进行混洗对从SQL获得的结果集没有影响。它不会随机地改变你的结果。删除Collections.shuffle(chksublist);并使用

String query = "SELECT * FROM Persons WHERE person_id IN (" + TextUtils.join(",", chksublist) + ") ORDER BY RANDOM()";

Answer 2

查看如何动态传递值

  // Getting single contact
 public Contact getContact(int id) {
SQLiteDatabase db = this.getReadableDatabase();

Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
        KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
        new String[] { String.valueOf(id) }, null, null, null, null);

 // here   new String[] { String.valueOf(id) } value is added dynamicaly which is passed to the function
if (cursor != null)
    cursor.moveToFirst();

Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
        cursor.getString(1), cursor.getString(2));
// return contact
return contact;
 }

Answer 3

您可以像这样生成查询

int values[];      //it contains your generated values like 21,22....
String query="SELECT * FROM Persons WHERE person_id IN (";

for(int i=0;i<values.length;i++){
query=query+"'"+values[i]+"'";
if(i<values.length-1){
query=query+",";    //No , after last values
} 

}
query+=")";

最后传递这个查询。