Android:SqliteDatabase 数据库的简单使用
- 其实做Android这么久还是对数据库这一块比较陌生，在实际项目中，没有搞过数据库这一块。对数据库总是有一些惧怕。
- 不小心看到慕课网有对数据库的讲解，于是根据讲解写了一个简单的Demo。
- 主要是熟悉一下sql语句，进行数据库的创建，表的创建，对表进行增删改查数据的操作。以及对
SQLiteOpenHelper的简单使用。 - 代码很少，且不涉及布局文件，所有的信息通过log去查看就好。
- 首先是
Activity的代码：
package com.duck.moocdatabase;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
public class MainActivity extends Activity {
private static final String STUDB = "studb";
private static boolean DELETE = true;
private static boolean UPDATE = true;
private static boolean INSERT = false;
private static boolean INSERT2 = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 创建第1张表 usertb
// opTableUsertb();
// 创建第二张表 stutb
// opTableStutb();
// 创建第3张表 ducktb
OpenDbHelper dbHelper = new OpenDbHelper(this, "duckInfo.db", null, 1);
SQLiteDatabase db = dbHelper.getWritableDatabase();
try {
Cursor cursor = db.query("fuckmetb", null, "_id>?",
new String[] { "0" }, null, null, "name");
if (cursor != null) {
String[] columnNames = cursor.getColumnNames();
while (cursor.moveToNext()) {
// 获取一条数据里面所有的信息
for (String columnName : columnNames) {
Log.d("System.out",
columnName
+ "***"
+ cursor.getString(cursor
.getColumnIndex(columnName)));
}
}
cursor.close();
}
db.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private void opTableStutb() {
SQLiteDatabase db = openOrCreateDatabase("user.db", MODE_PRIVATE, null);
String create = "create table if not exists studb(_id integer primary key autoincrement, name text not null, sex text not null, age integer not null)";
db.execSQL(create);
ContentValues values = new ContentValues();
if (INSERT2) {
values.clear();
values.put("name", "Doctor");
values.put("sex", "male");
values.put("age", 36);
db.insert(STUDB, null, values);// 1
values.clear();
values.put("name", "Teacher");
values.put("sex", "male");
values.put("age", 28);
db.insert(STUDB, null, values);// 2
values.clear();
values.put("name", "Husband");
values.put("sex", "female");
values.put("age", 36);
db.insert(STUDB, null, values);// 3
values.clear();
values.put("name", "Duck");
values.put("sex", "female");
values.put("age", 45);
db.insert(STUDB, null, values);// 4
values.clear();
values.put("name", "Cat");
values.put("sex", "female");
values.put("age", 26);
db.insert(STUDB, null, values);// 5
INSERT2 = false;
}
if (UPDATE) {
values.clear();
values.put("sex", "boy");
db.update(STUDB, values, "_id>?", new String[] { "3" });// 将所有的id>3的人的sex
// 该为 boy
UPDATE = false;
}
if (DELETE) {
values.clear();
db.delete(STUDB, "name like ?", new String[] { "%usb%" });// 删除name字段包含"usb"的数据的信息。
}
Cursor cursor = db.rawQuery("select * from STUDB", null);
if (cursor != null) {
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex("_id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
String sex = cursor.getString(cursor.getColumnIndex("sex"));
Log.v("System.out", "id=" + id + " | name=" + name + " | age="
+ age + " | sex=" + sex);
}
cursor.close();
}
System.out.println("============================");
Cursor query = db.query(STUDB, null, "_id>?", new String[] { "0" },
null, null, "age", null);
if (query != null) {
while (query.moveToNext()) {
String[] columnNames = query.getColumnNames();
for (String columnName : columnNames) {
String value = query.getString(query
.getColumnIndex(columnName));
Log.v("System.out", columnName + "=" + value);
}
}
query.close();
}
db.close();
}
private void opTableUsertb() {
// 1. 获取数据库对象
SQLiteDatabase db = openOrCreateDatabase("user.db", MODE_PRIVATE, null);
// 2.
String createTable = "create table if not exists usertb(_id integer primary key autoincrement, name text not null, age integer not null, sex text not null)";
db.execSQL(createTable);
if (INSERT) {
String insert1 = "insert into usertb(name,age,sex) values('ZhangSan','20','female')";
db.execSQL(insert1);
String insert2 = "insert into usertb(name,age,sex) values('LeeSi','19','female')";
db.execSQL(insert2);
String insert3 = "insert into usertb(name,age,sex) values('WangWu','21','male')";
db.execSQL(insert3);
}
String select = "select * from usertb";
Cursor cursor = db.rawQuery(select, null);
if (cursor != null) {
// cursor.moveToFirst();
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex("_id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
int age = cursor.getInt(cursor.getColumnIndex("age"));
String sex = cursor.getString(cursor.getColumnIndex("sex"));
Log.i("System.out", "id=" + id + " | name=" + name + " | age="
+ age + " | sex=" + sex);
}
cursor.close();
}
db.close();
}
}
Activity中，主要就是进行的数据库的两种方式的创建，数据库表的创建，增删改查的操作。- 然后是
SqilteOpenHelper的简单使用，利用该类进行数据库表的创建。
package com.duck.moocdatabase;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class OpenDbHelper extends SQLiteOpenHelper {
public OpenDbHelper(Context context, String name, CursorFactory factory,
int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable = "create table if not exists fuckmetb(_id integer primary key autoincrement, name text not null, age integer not null)";
db.execSQL(createTable);
String insertOneData = "insert into fuckmetb(name,age) values('YaZi',28)";
db.execSQL(insertOneData);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
以上代码运行ok。
* 关于数据库，还是了解甚少。
* 项目就不上传了，拷贝以上代码就可以直接运行。