剛剛開年,風輕雲淡。
昨天領導叫我用SQLite數據庫寫一個便籤。於是,我便寫了。
用數據庫寫便籤,無外乎就是對數據庫的增刪改查的一些操作,UI界面隨自己心意而定。
我今天主要也是說一些數據庫的操作。話不多說,我們進入正題。
Android提供了創建和是用SQLite數據庫的API。SQLiteDatabase代表一個數據庫對象,提供了操作數據庫的一些方法。在Android的SDK目錄下有sqlite3工具,我們可以利用它創建數據庫、創建表和執行一些SQL語句。下面是SQLiteDatabase的常用方法。
SQLiteDatabase的常用方法
public class MySqliteHelpe{
MySqlite mySqlite = null ;
SQLiteDatabase db = null ;
public MySqliteHelpe(Context context){
mySqlite = new MySqlite(context);
db = mySqlite.getReadableDatabase()
}
public void addUser(){
String sql = "insert info User__info (name , age) values ('coco' , '12')";
db.execSQL(sql);
}
public void findUser(){
String sql = "select * from user_info where name = ?";
Cursor cursor = db.rawQuery(sql , new String[]{"coco"});
cursor.moveToFirst();
while(cursor.isAfterLast){
String name = cursor.getString(cursor.getColumIndex("name"));
String age = cursor.getString(cursor.getColumIndex("age"));
cursor.maveToNext();
}
}
}
public class
MySqliteHelp {
MySqlite mySqlite = null ; SQLiteDatabase db = null ; public MySqliteHelp(Context context ){ mySqlite = new MySqlite(context); db = mySqlite.getReadableDatabase();
}
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創建數據庫幫助類 主要用來封裝對數據的操作(增刪改查)
聲明數據庫類的對象 聲明數據庫幫助類
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public void
addUser(String name){
String sql = "insert into user_info (name) values ('"+name+"')"; db.execSQL(sql); } /*
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添加用戶的方法 用到的語句
insert into 表名 (列名)values (‘“+傳進來的數據+”’)
db.execSQL(sql) 這句話的意思應該是執行上一句話
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public int
deleteUser(String name){
int sum = 0 ; ArrayList<String> arrayList = new ArrayList<>(); String sqq = "select * from user_info"; Cursor cursor = db.rawQuery(sqq , null); while(cursor.moveToNext()){ String user_name = cursor.getString(cursor.getColumnIndex("name")); arrayList.add(user_name); } cursor.close(); for(int i = 0 ; i<arrayList.size() ; i++){ String ss = arrayList.get(i).toString(); if(ss.equals(name)){ sum = 1; String sql = "delete from user_info where name = '"+name+"'"; db.execSQL(sql); break; } } return sum ; }
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public int
setUser(String name_on
,String name_off){
int sum = 0; ArrayList<String> arrayList = new ArrayList<>(); String sqq = "select * from user_info "; Cursor cursor = db.rawQuery(sqq , null); cursor.moveToFirst(); while(cursor.moveToNext()){ String ss = cursor.getString(cursor.getColumnIndex("name")); arrayList.add(ss); } cursor.close(); for(int i = 0 ; i<arrayList.size(); i++){ if(arrayList.get(i).toString().equals(name_on)){ sum = 1 ; String sql = "update user_info set name = '"+name_off+"' where name = '"+name_on+"'"; db.execSQL(sql); } } return sum ; } }
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public int
selectUser(String name){
int sum = 0 ; ArrayList<String> arrayList = new ArrayList<>(); String sql = "select * from user_info"; Cursor cursor = db.rawQuery(sql,null); cursor.moveToFirst(); while(cursor.moveToNext()){ String select_name = cursor.getString(cursor.getColumnIndex("name")); arrayList.add(select_name); } cursor.close(); for(int i = 0 ; i < arrayList.size(); i++){ if(arrayList.get(i).toString().equals(name)){ sum = 1; } } return sum ; }
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public
ArrayList<String>
findUser(){
String sql = "select * from user_info"; Cursor cursor = db.rawQuery(sql , null); cursor.moveToFirst(); ArrayList<String> arrayList = new ArrayList<>(); while(cursor.moveToNext()){ String name = cursor.getString(cursor.getColumnIndex("name")); arrayList.add(name); } return arrayList; }
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