Android(安卓)数据库操作 创建 添加 删除 查询
16lz
2021-12-04
第一步创建数据库工具类：
package com.mboss;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBHelper {
DBConnection helper;
public DBHelper(Context ctx) {
helper = new DBConnection(ctx);
}
public DBHelper() {
}
public void add(ContentValues values) {
SQLiteDatabase db = helper.getWritableDatabase();
db.insert(UserSchema.TABLE_NAME, null, values);
db.close();
}
public void DropTable(String TB_NAME) {
try {
SQLiteDatabase db = helper.getWritableDatabase();
String sql = "DROP TABLE " + TB_NAME;
db.execSQL(sql);
} catch (Exception ex) {
}
}
public void DropDatabase(Context ctx, String DATABASE_NAME) {
try {
ctx.deleteDatabase(DATABASE_NAME);
} catch (Exception ex) {
}
}
public void update(ContentValues values, String where, String[] whereArgs) {
SQLiteDatabase db = helper.getWritableDatabase();
db.update(UserSchema.TABLE_NAME, values, where, whereArgs);
db.close();
}
public void delete(String where, String[] whereArgs) {
SQLiteDatabase db = helper.getWritableDatabase();
db.delete(UserSchema.TABLE_NAME, where, whereArgs);
db.close();
}
public void delDB(String DBName) {
SQLiteDatabase db = helper.getWritableDatabase();
db.execSQL("DROP Database " + DBName);
db.close();
}
public List query(String where, String[] whereArgs, String orderBy,
String limit) {
try {
final SQLiteDatabase db = helper.getReadableDatabase();
Cursor c = null;
c = db.query(UserSchema.TABLE_NAME, null, where, whereArgs, null,
null, orderBy, limit);
List<CItem> lst = new ArrayList<CItem>();
while (c != null && c.moveToNext()) {
CItem item = new CItem();
item.setID(c.getString(c.getColumnIndex("m_key")));
item.setValue(c.getString(c.getColumnIndex("m_value")));
lst.add(item);
}
if (c != null)c.close();
return lst;
} catch (Exception e) {
// TODO: handle exception
}
return null;
}
public interface UserSchema {
String TABLE_NAME = "movement";
String ID = "m_id";
String TYPE = "m_type";
String Key = "m_key";
String Value = "m_value";
}
public static class DBConnection extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "SP.db";
private static final int DATABASE_VERSION = 1;
private DBConnection(Context ctx) {
super(ctx, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String create_sql = "CREATE TABLE movement(m_id integer primary key autoincrement,m_type varchar(10),"
+ "m_key varchar(20),m_value varchar(100),m_order integer)";
db.execSQL(create_sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
// String alter_sql = "ALTER TABLE movement";
// db.execSQL(alter_sql);
}
}
}
使用数据库如下代码：
public DBHelper getDb() {
if (db == null)
db = new DBHelper(this);
return db;
}
添加：
ContentValues cv = new ContentValues();
cv.put("m_type", type);
cv.put("m_key", key);
cv.put("m_value", value);
getDb().add(cv);
查询：
List<CItem> lst = getDb().query("m_type=?", new String[] { cmd }, null, null);
创建后的数据库在
cd datat/data/当前项目包名/databases
http://www.seewn.com/
相关技术帖子：http://blog.sina.com.cn/gzwncb
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