sqlite基础知识介绍
1.sqlite数据库数据类型
Integer varchar(10) float double char(10) text
2.数据库语句
2.1创建表语句
create table person(-id Integer primary key, name varchar(10), age Integer not null)
2.2删除表语句
drop table person
2.3插入语句
Insert into person(_id, age) values(1,20)
2.4修改语句
update person set name="ls", age=20 where _id=10
2.5删除数据
delete from person where _id=1
2.6查询语句
select 字段名 from 表名 where 查询条件 group by 分组字段 having 筛选条件 order by 排序字段
select * from person;
select * from person where age between 10 and 20;
sqlite Demo应用
Constant.java:
package com.czhappy.sqlitedemo.utils;
/**
* Description:
* User: chenzheng
* Date: 2016/11/10 0010
* Time: 10:42
*/
public class Constant {
public static final String DATABASE_NAME = "info.db";
public static final int DATABASE_VERSION = 1;
public static final String TABLE_NAME = "person";
public static final String _ID = "_id";
public static final String NAME = "name";
public static final String AGE = "age";
}
MySqliteHelper.java:
package com.czhappy.sqlitedemo.utils;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
/**
* Description:
* User: chenzheng
* Date: 2016/11/10 0010
* Time: 10:37
*/
public class MySqliteHelper extends SQLiteOpenHelper{
public MySqliteHelper(Context context){
super(context, Constant.DATABASE_NAME, null, Constant.DATABASE_VERSION);
}
public MySqliteHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
/**
* 数据库创建调用
* @param db
*/
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "create table "+Constant.TABLE_NAME+"(" + Constant._ID
+" Integer primary key,"+Constant.NAME+" varchar(10),"
+Constant.AGE +" Integer)";
db.execSQL(sql);
}
/**
*
* 数据库版本更新回调函数
* @param db
* @param oldVersion
* @param newVersion
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
/**
* 数据库打开回调函数
* @param db
*/
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
}
}
DbManager.java:
package com.czhappy.sqlitedemo.utils;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
/**
* Description:数据库操作工具类
* User: chenzheng
* Date: 2016/11/10 0010
* Time: 10:46
*/
public class DbManager {
public static MySqliteHelper helper;
public static MySqliteHelper getInstance(Context context){
if(helper==null){
helper = new MySqliteHelper(context);
}
return helper;
}
public static void execSql(SQLiteDatabase db, String sql){
if(db!=null){
if(sql!=null && !"".equals(sql)){
db.execSQL(sql);
}
}
}
}
MainActivity.java:
package com.czhappy.sqlitedemo;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Toast;
import com.czhappy.sqlitedemo.utils.Constant;
import com.czhappy.sqlitedemo.utils.DbManager;
import com.czhappy.sqlitedemo.utils.MySqliteHelper;
public class MainActivity extends AppCompatActivity {
private MySqliteHelper helper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
helper = DbManager.getInstance(this);
}
public void createDb(View view){
SQLiteDatabase db = helper.getWritableDatabase();
}
public void click(View view){
switch (view.getId()){
case R.id.insert_btn:
SQLiteDatabase db = helper.getWritableDatabase();
String sql = "insert into "+ Constant.TABLE_NAME+" values(1, 'lisi', 20)";
DbManager.execSql(db, sql);
db.close();
break;
case R.id.update_btn:
db = helper.getWritableDatabase();
sql = "update "+ Constant.TABLE_NAME+" set name='xiaoming' where _id=1";
DbManager.execSql(db, sql);
db.close();
break;
case R.id.delete_btn:
db = helper.getWritableDatabase();
sql = "delete from "+ Constant.TABLE_NAME+" where _id=1";
DbManager.execSql(db, sql);
db.close();
break;
case R.id.insertApi_btn:
db = helper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(Constant._ID, 3);
values.put(Constant.NAME, "zhangsan");
values.put(Constant.AGE, 30);
long result = db.insert(Constant.TABLE_NAME, null, values);
if(result>0){
Toast.makeText(MainActivity.this, "插入数据成功", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(MainActivity.this, "插入数据失败", Toast.LENGTH_SHORT).show();
}
db.close();
break;
case R.id.updateApi_btn:
db = helper.getWritableDatabase();
values = new ContentValues();
values.put(Constant.NAME, "qianliu");
int count = db.update(Constant.TABLE_NAME,values, Constant._ID+"=?", new String[]{"3"});
if(count>0){
Toast.makeText(MainActivity.this, "修改数据成功", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(MainActivity.this, "修改数据失败", Toast.LENGTH_SHORT).show();
}
db.close();
break;
case R.id.deleteApi_btn:
db = helper.getWritableDatabase();
values = new ContentValues();
values.put(Constant._ID, 3);
int count2 = db.delete(Constant.TABLE_NAME, Constant._ID+"=?", new String[]{"3"});
if(count2>0){
Toast.makeText(MainActivity.this, "删除数据成功", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(MainActivity.this, "删除数据失败", Toast.LENGTH_SHORT).show();
}
db.close();
break;
}
}
}
