Android开发工程师文集-1 小时学会SQLite

Posted 2020-12-03 程序员哆啦A梦

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前言

大家好，给大家带来android开发工程师文集-1 小时学会SQLite的概述，希望你们喜欢

内容

什么是Sqlite：
效率高，开源，小型，程序驱动，支持事务操作，无数据类型，可嵌入的关系型数据库
独立的，跨平台的，代码量少，简单易用

创建表语句

create table student(_id Integer primary key, name varchar(10), age Integer not null);

删除表

drop table student;

插入数据

Insert into 表名(字段列表) values (值列表);
insert into student(_id,age) values(1,17);
insert into student values(1,"vic",17);

修改数据

update student set name="vic",age=17 where _id=1;

更新数据

Update 表名 set 字段=值 列表 更新的条件

删除数据

delete from 表名 [删除条件];
delete from student where _id=1;

查询语句

select 字段名 from 表名称 [查询条件];
select 列名称 from 表名称 where 条件;
group by 分组的字段 having 筛选条件 order by 排序字段;
select * from student;
select _id from student;
select * from student where _id=1;
select * from student where _id=1 and age>17;
select * from student where age like "%1%";
select * from student where age>17 order by _id=1;

内容

创建数据库
实现数据库中的增删改查

要点

SQLiteOpenHelper,onCreate(),onUpgrade(),onOpen()

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_bg"
    android:orientation="vertical">
 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="创建"
  android:onClick="create"
  android:background="#000000"/>
</LinearLayout>

//MainActivity.java
public class MainActivity extends AppCompatActivity {
  private mysqliteHelper helper;
 @Override
 protected void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 helper = DbManger.getIntance(this);
 }
 public void createdb(View view){
  SQLiteDatabase db=helper.getWritableDatable();
 }
}

//创建一个类
//sqliteOpenHelper
//提供了onCreate()和onUpgrade()与onOpen()
public class MySqliteHelper extends SQLiteOpenHelper{
 public MySqliteHelper(Context context, String name, SQLitebase.CursorFactory factory, int version){
 super(context,name,factory,version);
 }
 public MySqliteHelper(Context context){
  super(context,Constant.DATABASE_NAME,null,Constant.DATABASE_VERSION);
}
 //数据库创建时回调
 @Override
 public void onCreate(SQLiteDatabase db){
  Log.i("tag","--onCreate--");
  //String sql="create table student(_id Integer primary key,name verchar(10),age Integer)";
  String sql = "create table "+Constant.TABLE_NAME+"("+Constant._ID+" Integer primary key,"+Constant.NAME+" varchar(10),"+Constant.AGE+" Integer)";
  db.execSQL(sql);//执行数据库语句
 }
 //数据库更新
 @Override
 public void onUpgrade(SQLiteDatabase db,int oldVersion, int newVersion){
  Log.i("tag","--onUpgrade--");
 }
 //数据库打开
 @Override
 public void onOpen(SQLiteDatabase db){
  super.onOpen(db);
  Log.i("tag","--onOpen--");
 }
}

//创建库表
public class Contant{
 public static final String DATABASE_NAME=“info.db”;//数据库名称
 public static final int DATABASE_VERSION=1;//数据库的版本号
 public static final String TABLE_NAME="student";//表名
  //用这里表示
 public static final String _ID="_id";
 public static final String _NAME="name";
 public static final String AGE="age";

public class DbManger{
 private static MySqliteHelper helper;
 public static MySqliteHelper getIntance(Context context){
   if(helper == null){
     helper=new MySqliteHelper(content);
   }
   return hepler;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_bg"
    android:orientation="vertical">
 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="创建"
  android:onClick="create"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_insert"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
</LinearLayout>

//MainActivity.java
public class MainActivity extends AppCompatActivity {
  private MySqliteHelper helper;
 @Override
 protected void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 helper = DbManger.getIntance(this);
 }
 public void createdb(View view){
  SQLiteDatabase db=helper.getWritableDatable();
 }
 public void click(View view){
  switch(view.getId()){
   case R.id.btn_insert:
    SQLiteDatabase db=helper.getWritableDatabase();
    String sql="insert into "+Constant.TABLE_NAME+" values(1,'vic',17)";
    DbManger.execSQL(db,sql);
    String sql2="insert into "+Constant.TABLE_NAME+" values(2,'vic',23)";
    DbManger.execSQL(db,sql2);
    db.close();
    break;
 }
}

public class DbManger{
 private static MySqliteHelper helper;
 public static MySqliteHelper getIntance(Context context){
   if(helper == null){
     helper=new MySqliteHelper(content);
   }
   return hepler;
 }
 public static void execSQL(SQLiteDatabase db,String sql){
  if(db!=null){
   if(sql!=null && !"".equals(sql)){
     db.execSQL(sql);
  }
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_bg"
    android:orientation="vertical">
 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="创建"
  android:onClick="create"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_insert"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_update"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="修改数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
</LinearLayout>

//MainActivity.java
public class MainActivity extends AppCompatActivity {
  private MySqliteHelper helper;
 @Override
 protected void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 helper = DbManger.getIntance(this);
 }
 public void createdb(View view){
  SQLiteDatabase db=helper.getWritableDatable();
 }
 public void click(View view){
  switch(view.getId()){
   case R.id.btn_insert:
    SQLiteDatabase db=helper.getWritableDatabase();
    String sql="insert into "+Constant.TABLE_NAME+" values(1,'vic',17)";
    DbManger.execSQL(db,sql);
    String sql2="insert into "+Constant.TABLE_NAME+" values(2,'vic',23)";
    DbManger.execSQL(db,sql2);
    db.close();
    break;
   case R.id.btn_update:
    db=helper.getWritableDatabase();
    String updateSql="update "+Constant.TABLE_NAME"+" set "+Contant.NAME+"='vic2' where "+Contant._ID+"=1";
    DbManger.execSQL(db,updateSql);
    db.close();
    break;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_bg"
    android:orientation="vertical">
 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="创建"
  android:onClick="create"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_insert"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_update"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="修改数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_delete"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="删除数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
</LinearLayout>

//MainActivity.java
public class MainActivity extends AppCompatActivity {
  private MySqliteHelper helper;
 @Override
 protected void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 helper = DbManger.getIntance(this);
 }
 public void createdb(View view){
  SQLiteDatabase db=helper.getWritableDatable();
 }
 public void click(View view){
  switch(view.getId()){
   case R.id.btn_insert:
    SQLiteDatabase db=helper.getWritableDatabase();
    String sql="insert into "+Constant.TABLE_NAME+" values(1,'vic',17)";
    DbManger.execSQL(db,sql);
    String sql2="insert into "+Constant.TABLE_NAME+" values(2,'vic',23)";
    DbManger.execSQL(db,sql2);
    db.close();
    break;
   case R.id.btn_update:
    db=helper.getWritableDatabase();
    String updateSql="update "+Constant.TABLE_NAME"+" set "+Contant.NAME+"='vic2' where "+Contant._ID+"=1";
    DbManger.execSQL(db,updateSql);
    db.close();
    break;
   case R.id.btn_delete:
    db=helper.getWritableDatabase();
    String delSql="delete from "+Constant.TABLE_NAME+" where "+Constant._ID+"=2";
    DbManger.execSQL(db,delSql);
    db.close();
    break;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/login_bg"
    android:orientation="vertical">
 <Button
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="创建"
  android:onClick="create"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_insert"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_update"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="修改数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_delete"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="删除数据"
  android:onClick="click"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_insertApi"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="onclick"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
</LinearLayout>

//MainActivity.java
public class MainActivity extends AppCompatActivity {
  private MySqliteHelper helper;
 @Override
 protected void onCreate(Bundle savedInstanceState){
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 helper = DbManger.getIntance(this);
 }
 public void createdb(View view){
  SQLiteDatabase db=helper.getWritableDatable();
 }
 public void onClick(View view){
  switch(view.getId()){
   case R.id.btn_insertApi:
    SQLiteDatabase db=helper.getWritableDatabase();
    ContentValues values=new ContentValues();
    values.put(Constant._ID,3);
    values.put(Constant.NAME,"vic");
    values.put(Constant.AGE,17);
    long result=db.insert(Constant.TABLE_NAME,null,values);
    if(result>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
    db.close();
    break;
   }
}

 public void click(View view){
  switch(view.getId()){
   case R.id.btn_insert:
    SQLiteDatabase db=helper.getWritableDatabase();
    String sql="insert into "+Constant.TABLE_NAME+" values(1,'vic',17)";
    DbManger.execSQL(db,sql);
    String sql2="insert into "+Constant.TABLE_NAME+" values(2,'vic',23)";
    DbManger.execSQL(db,sql2);
    db.close();
    break;
   case R.id.btn_update:
    db=helper.getWritableDatabase();
    String updateSql="update "+Constant.TABLE_NAME"+" set "+Contant.NAME+"='vic2' where "+Contant._ID+"=1";
    DbManger.execSQL(db,updateSql);
    db.close();
    break;
   case R.id.btn_delete:
    db=helper.getWritableDatabase();
    String delSql="delete from "+Constant.TABLE_NAME+" where "+Constant._ID+"=2";
    DbManger.execSQL(db,delSql);
    db.close();
    break;
 }
}

<Button
  android:id="@+id/btn_insertApi"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="插入数据"
  android:onClick="onclick"
  android:layout_marginTop="15dp"
  android:background="#000000"/>
<Button
  android:id="@+id/btn_updateApi"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="更新数据"
  android:onClick="onclick"
  android:layout_marginTop="15dp"
  android:background="#000000"/>

public void onClick(View view){
  switch(view.getId()){
   case R.id.btn_insertApi:
    SQLiteDatabase db=helper.getWritableDatabase();
    ContentValues values=new ContentValues();
    values.put(Constant._ID,3);
    values.put(Constant.NAME,"vic");
    values.put(Constant.AGE,17);
    long result=db.insert(Constant.TABLE_NAME,null,values);
    if(result>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
    db.close();
    break;
   case R.id.btn_updateApi:
    //String table 修改的数据表的名称,ContentValues values,String whereClause 表示修改条件,String[] whereArgs
    db=helper.getWritableDatabase();
    //db.update(String table,ContentValues values,String whereClause,String[] whereArgs);
    ContentValues cv=new ContentValues();
    cv.put(Contant.NAME,"vic3");
    int count=db.update(Constant.TABLE_NAME,cv,Contant.TABLE_NAME,cv,Constant._ID+"=?",new String[]{"3"});
    if(count>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
    db.close();
    break;
   }
}

<Button
  android:id="@+id/btn_updateApi"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="更新数据"
  android:onClick="onclick"
  android:layout_marginTop="15dp"
  android:background="#000000"/>

public void onClick(View view){
  switch(view.getId()){
   case R.id.btn_insertApi:
    SQLiteDatabase db=helper.getWritableDatabase();
    ContentValues values=new ContentValues();
    values.put(Constant._ID,3);
    values.put(Constant.NAME,"vic");
    values.put(Constant.AGE,17);
    long result=db.insert(Constant.TABLE_NAME,null,values);
    if(result>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
    db.close();
    break;
   case R.id.btn_updateApi:
    //String table 修改的数据表的名称,ContentValues values,String whereClause 表示修改条件,String[] whereArgs
    db=helper.getWritableDatabase();
    //db.update(String table,ContentValues values,String whereClause,String[] whereArgs);
    ContentValues cv=new ContentValues();
    cv.put(Contant.NAME,"vic3");
    int count=db.update(Constant.TABLE_NAME,cv,Contant.TABLE_NAME,cv,Constant._ID+"=?",new String[]{"3"});
    if(count>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
    db.close();
    break;
  case R.id.btn_deleteApi:
  db=helper.getWritableDatabase();

  //int count2=db.delete(String table,StringwhereClause,String[] whereArgs);
  int count2=db.delete(Constant.TABLE_NAME,Constant._ID+"=?",new String[]{"1"});
  if(count2>0){
     Toast.makeText(MainActivity.this,"插入数据成功!",Toast.LENGTH_LONG).show();
    }else{
      Toast.makeText(MainActivity.this,"插入数据失败!",Toast.LENGTH_LONG).show();
    }
  db.close();
  break;
}

 public int delete(String table,String whereClause,String[] whereArgs){
  acquireReference();
  try{
   SQLiteStatement statement = new SQLiteStatement(this,"DELETE FROM "+table+(!TextUtils.isEmpty(whereClause) ? " WHERE "+whereClause : ""), whereArgs;
 try{
  return statement.executeUpdateDelete();
  }finally{
   statement.close();
  }
  }finally{
  releaseReference();
}

总结

本文讲了Android开发工程师文集-1 小时学会SQLite，如果您还有更好地理解，欢迎沟通
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