Question

我在DatabaseHelper.kt中有一个函数：

fun readData_Inventory(barcode: String): Inventory{ 
        val p0 = this.readableDatabase
        val selection = "$COL_PRODUCTID = ?"
        val selectionArgs = arrayOf(barcode)
        val cursor = p0.query(TABLE_INVENTORY, null, selection, selectionArgs,null, null, null)
        Toast.makeText(context, "Barcode: $barcode, Count: ${cursor.count}", Toast.LENGTH_LONG).show()
        val inventory: Inventory?
        if (cursor.moveToLast()) {
            cursor.moveToLast()
            val productId = cursor.getString(cursor.getColumnIndex(COL_PRODUCTID))
            val quantity = cursor.getDouble(cursor.getColumnIndex(COL_QUANTITY))
            val source = cursor.getString(cursor.getColumnIndex(COL_SOURCE))
            val dateCheck = cursor.getString(cursor.getColumnIndex(COL_DATECHECK))
            inventory = Inventory(productId, quantity, source, dateCheck)
        } else{
            inventory = Inventory ("000", 0.0, "", "")
        }
        return inventory

但是Toast在cursor.count中显示0。

我知道表中有行，因为当我运行下一个代码时，它会带出我要查找的行：

fun readData_Inventory(barcode: String): Inventory{ 
        val p0 = this.readableDatabase
        val sql = "select * from $TABLE_INVENTORY"
        val cursor = p0.rawQuery(sql, null)
        val inventory: Inventory?
        Toast.makeText(context, "Barcode: $barcode, Count: ${cursor.count}", Toast.LENGTH_LONG).show()
        if (cursor.moveToLast()) {
            cursor.moveToLast()
            val productId = cursor.getString(cursor.getColumnIndex(COL_PRODUCTID))
            val quantity = cursor.getDouble(cursor.getColumnIndex(COL_QUANTITY))
            val source = cursor.getString(cursor.getColumnIndex(COL_SOURCE))
            val dateCheck = cursor.getString(cursor.getColumnIndex(COL_DATECHECK))
            inventory = Inventory(productId, quantity, source, dateCheck)
        } else{
            inventory = Inventory ("000", 0.0, "", "")
        }
        return inventory

感谢您的帮助。预先感谢。

编辑： 我尝试了下一个代码：

fun readData_Inventory(barcode: String) {
        val p0 = this.readableDatabase
        val inventory: Inventory?
        val sql = "select * from $TABLE_INVENTORY"
        val cursor = p0.rawQuery(sql, null)
        Toast.makeText(context, "Size: ${cursor.count} Move: ${cursor.moveToFirst()}", Toast.LENGTH_LONG).show()
        /////////////////
        cursor.moveToFirst()
        val productId = cursor.getString(cursor.getColumnIndex(COL_PRODUCTID))
        Toast.makeText(context, "ID: $productId", Toast.LENGTH_LONG).show()
    }

当我仅使用第一部分（在////////部分之前）运行代码时，吐司显示"Size: 1, true"（没关系，我的表只有一行）。但是，当我添加第二部分（在////////之后）时，显示错误：android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0

我正在添加插入数据的部分...也许是...

fun insertData_Inventory(inventory: Inventory){
        val p0 = this.writableDatabase
        val cv = ContentValues()
        cv.put(COL_PRODUCTID, inventory.product_id)
        cv.put(COL_QUANTITY, inventory.quantity)
        cv.put(COL_SOURCE, inventory.source)
        cv.put(COL_DATECHECK, inventory.checkDate)
        val result = p0.insert(TABLE_INVENTORY, null, cv)
        if (result == (-1).toLong())
            Toast.makeText(context, "Insert Inventory Failed", Toast.LENGTH_SHORT).show()
        else
            Toast.makeText(context, "Insert Inventory Success", Toast.LENGTH_SHORT).show()
        p0.close()
    }

它总是插入并显示“插入库存成功”

还有我声明表的部分：

val TABLE_INVENTORY = "Inventory"
val COL_INVENTORYID = "inventory_id"
val COL_PRODUCTID = "product_id"
val COL_QUANTITY = "quantity"
val COL_SOURCE = "source"
val COL_DATECHECK = "date_check"
val CREATE_T_INVENTORY = "CREATE TABLE if not exists $TABLE_INVENTORY " +
        "(" +
        "$COL_INVENTORYID integer PRIMARY KEY, " +
        "$COL_PRODUCTID varchar(20), " +
        "$COL_QUANTITY double, " +
        "$COL_SOURCE varchar(20)," +
        "$COL_DATECHECK datetime, " +
        "FOREIGN KEY($COL_PRODUCTID) REFERENCES $TABLE_PRODUCT($COL_PRODUCTID)" +
        ")"

还有其他想法吗？预先感谢！

Answer 1

在rawquery中尝试整个语句：

val sql = "select * from $TABLE_INVENTORY WHERE trim($COL_PRODUCTID) = '$barcode'"
val cursor = p0.rawQuery(sql, null)

我认为条形码是TEXT

Answer 2

在初始化对象时，我错过了一行：

inventory.product_id = product.product_id

尤其是@mTak

无法从数据库获取行。 SQLite，Android，Kotlin

2 个答案: