sqlite的使用

1.创建一个类继承SQLiteOpenHelper并重写父类的onCreate（）方法，添加一个构造方法。在onCreate方法中编写创建表的语句。

public class DatabaseHelper extends SQLiteOpenHelper {
    public static final String PRODUCT_TABLE_NAME = "productNotupload";
    public static final String USERNAME = "username";
    public static final String  PRODUCTNAME= "product_name";
    public static final String RECORDTIME = "transact_date";
    public static final String FILEPATH = "filepath";
    public static final String TRADENO = "tradeno";
    public static final String DATABASE_NAME = "jingan.db";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + PRODUCT_TABLE_NAME + "(" + USERNAME + " varchar(20) not null, " + PRODUCTNAME + " varchar(60) not null," +
                RECORDTIME + " varchar(20) not null," + FILEPATH + " varchar(200) not null," + TRADENO + " varchar(20) not null )");
    }

2. 使用：在需要使用该表时，先初始化数据库对象得到操作权限，从而进行insert，delete , update,query操作。

DatabaseHelper databaseHelper = new DatabaseHelper(this);  //获取数据库对象
mSqLiteDatabase = databaseHelper.getWritableDatabase(); //获取写权限

//添加 insert
ContentValues contentValues = new ContentValues();
        contentValues.put(DatabaseHelper.USERNAME, username);
        contentValues.put(DatabaseHelper.PRODUCTNAME, productName);
        contentValues.put(DatabaseHelper.RECORDTIME, recordTime);
        contentValues.put(DatabaseHelper.FILEPATH, filepath);
        contentValues.put(DatabaseHelper.TRADENO, tradeno);
        mSqLiteDatabase.insert(DatabaseHelper.PRODUCT_TABLE_NAME, null, contentValues);

//删除 delete
mSqLiteDatabase.delete(DatabaseHelper.PRODUCT_TABLE_NAME, whereClauseString, whereArgsString);

//查询 query
 Cursor cursor = mSqLiteDatabase.query(DatabaseHelper.PRODUCT_TABLE_NAME, columns, null, null, null, null, null);

        while (cursor.moveToNext()) {
                String userName = cursor.getString(cursor.getColumnIndexOrThrow(DatabaseHelper.USERNAME));
                String productName = cursor.getString(cursor.getColumnIndexOrThrow(DatabaseHelper.PRODUCTNAME));
                String recordTime = cursor.getString(cursor.getColumnIndexOrThrow(DatabaseHelper.RECORDTIME));
                String filepath = cursor.getString(cursor.getColumnIndexOrThrow(DatabaseHelper.FILEPATH));
                String tradeno = cursor.getString(cursor.getColumnIndexOrThrow(DatabaseHelper.TRADENO));
                UnVerifyModel unVerifyModel = new UnVerifyModel(userName,productName,recordTime,filepath,tradeno);
                lists.add(unVerifyModel);
                Log.e("-----------------------",  ":" + userName + "|" + productName + "|" + recordTime + "|" + filepath + "|" + tradeno + "/n");
            }