我正在制作关于伊斯兰教的最后一年项目。我想在其中使用SQLite数据库。但我无法简单地在其中创建数据库。我想在其中添加每日namaz出勤率。 第二个我如何设置列的类型到目前为止帮帮我....在此先感谢.. !!!
DataBaseHelper.java
package com.example.shakeelmughal.assanislam;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/**
* Created by Shakeel Mughal on 5/29/2018.
*/
public class DataBaseHelper extends SQLiteOpenHelper {
public static final String databasename="Test.db";
public static final String Tbname = "student_table";
public static final String Col_1 = "ID";
public static final String Col_2 = "Name";
public static final String Col_3 = "Class";
public static final String Col_4 = "Marks";
public DataBaseHelper(Context context) {
super(context, databasename, null, 1);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
sqLiteDatabase.execSQL("CREATE TABLE "+Tbname+"(ID INTEGER PRIMARY KEY AUTOINCREMENT, Name TEXT, Class TEXT, Marks INTEGER)");
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS "+Tbname);
onCreate(sqLiteDatabase);
}
}
我对数据库的主要活动 NamazCounterActivity，JAVA
package com.example.shakeelmughal.assanislam;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.Toast;
public class NamazCounterActivity extends AppCompatActivity {
DataBaseHelper mydb;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_namaz_counter);
mydb = new DataBaseHelper(this);
mydb.getWritableDatabase();
//home button
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
}
}
//function for going back to previous activity
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId() == android.R.id.home)
finish();
return super.onOptionsItemSelected(item);
}
}
答案 0 :(得分：0)
您的代码工作正常，例如使用您的代码导致： -
Database Version = 1
Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table Name = student_table Created Using = CREATE TABLE student_table(ID INTEGER PRIMARY KEY AUTOINCREMENT, Name TEXT, Class TEXT, Marks INTEGER)
Table = student_table ColumnName = ID ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
Table = student_table ColumnName = Name ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table = student_table ColumnName = Class ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table = student_table ColumnName = Marks ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
Table Name = sqlite_sequence Created Using = CREATE TABLE sqlite_sequence(name,seq)
因此答案 ＆＃34;无法创建简单的数据库 ＆＃34;
SQLite中的日期没有特定的数据类型。实际上在SQLite中，类型并不是全部相关，因为您可以在任何类型的列中存储任何类型的值（除了 rowid 列的别名，只能是INTEGER）。
重要的是保存数据的方式。以可识别的格式/类型存储日期具有明显的优势。
e.g。按照： -
2.2。日期和时间数据类型SQLite没有为存储日期和/或时间而预留的存储类。相反，内置的日期和 SQLite的时间函数能够存储日期和时间 TEXT，REAL或INTEGER值：
TEXT as ISO8601 strings（＆＃34; YYYY-MM-DD HH：MM：SS.SSS＆＃34;）。真如朱利安 日数，11月以来格林威治中午以来的天数 公元前24,4714根据公历格里高利历。整数 as Unix Time，自1970-01-01 00:00:00 UTC以来的秒数。 应用程序可以选择在任何这些中存储日期和时间 使用内置日期格式和格式之间自由转换 时间功能。
简而言之，上面的链接必须阅读并且确实是您的问题的答案 ＆＃34;我如何设置列的类型到目前为止＆＃34; 。它还扩展了给出的简要概述。
您可能还会发现此链接很有用Date And Time Functions
以下代码是列类型的灵活性，如何存储日期以及存储访问数据的一般方法的示例。使用您的数据库和表格（参见注释和注释）： -
DBHelper mydb; //<<<< Note the DatabaseHelper class has been renamed for my convenience
mydb = new DBHelper(this);
SQLiteDatabase sqldb = mydb.getWritableDatabase();
sqldb.delete(DBHelper.Tbname,null,null); //<<<< delete all rows, if any
//Prepare to insert a row
ContentValues cv = new ContentValues();
cv.put(DBHelper.Col_2,"2018-01-01 10:30:00"); //<<<< recognised date format
cv.put(DBHelper.Col_3,100.99D); //<<<< Double into a column defined as TEXT
cv.put(DBHelper.Col_4, "Sorry you scored nothing"); //<<<< Text into an INTEGER
sqldb.insert(
DBHelper.Tbname,
null,
cv
);
cv.clear();
// Prepare to insert a 2nd row
cv.put(DBHelper.Col_2,"Fred");
cv.put(DBHelper.Col_3,System.currentTimeMillis()); //<<<<< can be used stores long as INTEGER
sqldb.insert(DBHelper.Tbname,null,cv);
// get all the rows from the table
Cursor csr = sqldb.query(DBHelper.Tbname,
null,
null,
null,
null,
null,
null
);
while (csr.moveToNext()) {
Log.d("DATA",
"ROW " + csr.getPosition() +
" has a value of " +
String.valueOf(csr.getLong(csr.getColumnIndex(DBHelper.Col_1))) +
" in the " + DBHelper.Col_1 +
" column, a value of " +
csr.getString(csr.getColumnIndex(DBHelper.Col_2)) +
" in the " +
DBHelper.Col_2 +
" column, a value of " +
csr.getString(csr.getColumnIndex(DBHelper.Col_3)) +
" in the " +
DBHelper.Col_3 +
" column, and a value of " +
csr.getString(csr.getColumnIndex(DBHelper.Col_4)) +
" in the " +
DBHelper.Col_4 +
" column."
);
}
csr.close(); //<<<< Should always close a Cursor when done with it
以上结果输出到日志： -
ROW 0 has a value of 5 in the ID column, a value of 2018-01-01 10:30:00 in the Name column, a value of 100.99 in the Class column, and a value of Sorry you scored nothing in the Marks column.
ROW 1 has a value of 6 in the ID column, a value of Fred in the Name column, a value of 1527600028305 in the Class column, and a value of null in the Marks column.