wYDmzF9Y

1MyDBHandler.kt
2=================
3package com.example.mysqllite
4
5import android.content.ContentValues
6import android.content.Context
7import android.database.sqlite.SQLiteDatabase
8import android.database.sqlite.SQLiteOpenHelper
9
10class MyDBHandler(
11    context: Context,
12    name: String?,
13    factory: SQLiteDatabase.CursorFactory?,
14    version: Int
15) : SQLiteOpenHelper(context, DATABASE_NAME, factory, DATABASE_VERSION) {
16    override fun onCreate(db: SQLiteDatabase) {
17        val CREATE_PRODUCTS_TABLE =
18            ("CREATE TABLE IF NOT EXITS $TABLE_PRODUCTS ($COLUMN_ID INTEGER PRIMARY KEY, $COLUMN_PRODUCTNAME TEXT, $COLUMN_QUANTITY INTEGER)")
19        db.execSQL(CREATE_PRODUCTS_TABLE)
20    }
21
22    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
23        /* it will erase yours existing table with all it's data without asking nothing
24        db.execSQL("DROP TABLE IF EXISTS ${TABLE_PRODUCTS}")
25        onCreate(db)
26        */
27    }
28
29    companion object {
30        private val DATABASE_VERSION = 1
31        private val DATABASE_NAME = "productDB.db"
32        val TABLE_PRODUCTS = "products"
33
34        //declare of columns names
35        val COLUMN_ID = "_id"
36        val COLUMN_PRODUCTNAME = "productname"
37        val COLUMN_QUANTITY = "quantity"
38    }
39
40    //add product
41    fun addProduct(product: Product) {
42        //give values to our database data
43        val values = ContentValues()
44        values.put(COLUMN_PRODUCTNAME, product.productName)
45        values.put(COLUMN_QUANTITY, product.quantity)
46
47        //give write access to the database
48        val db = this.writableDatabase
49
50        //insert the data into the database
51        db.insert(TABLE_PRODUCTS, null, values)
52
53        //close the database
54        db.close()
55    }
56
57    //find product
58    fun findProduct (productName:String):Product?{
59        //SELECT * FROM TABLE WHERE COLUMN = ""  \" -> "
60        val query = "SELECT * FROM $TABLE_PRODUCTS WHERE $COLUMN_PRODUCTNAME = \"$productName\""
61        val db =  this.writableDatabase
62        val cursor = db.rawQuery(query,null)
63        var product:Product? = null
64
65        // [product 1] [product 2] ...  [product N]
66        if (cursor.moveToFirst()){
67            cursor.moveToFirst()
68
69            val id = Integer.parseInt(cursor.getString(0))
70            val name = cursor.getString(1)
71            val quantity = Integer.parseInt(cursor.getString(2))
72
73            product = Product(id,name,quantity)
74            cursor.close()
75        }
76        db.close()
77        return product
78    }
79
80    //delete product
81    fun deleteProduct(productName: String):Boolean{
82        var result = false
83        val query = "SELECT * FROM $TABLE_PRODUCTS WHERE $COLUMN_PRODUCTNAME = \"$productName\""
84
85        val  db =  this.writableDatabase
86        val cursor = db.rawQuery(query,null)
87
88        if  (cursor.moveToFirst()){
89            val id = Integer.parseInt(cursor.getString(0))
90            db.delete(TABLE_PRODUCTS, "$COLUMN_ID = ?", arrayOf(id.toString()))
91            cursor.close()
92            result = true
93        }
94        db.close()
95        return result
96    }
97}
98
99
100Product.kt
101===================
102package com.example.mysqllite
103
104class Product {
105    //id
106    //productName
107    //quantity
108
109    //id,productName,quantity
110    //productName,quantity
111
112
113    var id: Int = 0
114    var productName: String? = null
115    var quantity: Int = 0
116
117    constructor(id: Int, productName: String, quantity: Int) {
118        this.id = id
119        this.productName = productName
120        this.quantity = quantity
121    }
122
123    constructor(productName: String, quantity: Int){
124        this.productName=productName
125        this.quantity=quantity
126    }
127
128}