Android SQLite数据库
前言
以前写PHP的时候，内置了print_r()和var_dump()两个函数用于打印输出任意类型的数据内部结构，现在做Android的开发，发现并没有这种类似的函数，对于数据库的查看很不方便，于是就写了一下查看数据库表的方法代码。
代码实现
import java.util.Arrays;
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class SecondActivity extends Activity {
public static final String TAG = "Debug Info";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
((Button)findViewById(R.id.btnQue)).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
MyDatabaseHelper dbhelper = new MyDatabaseHelper(SecondActivity.this, "BookStore.db", null, 1);
SQLiteDatabase db = dbhelper.getWritableDatabase();
//核心区
//读取系统表 sqlite_master
String sql = "select * from sqlite_master";
Cursor cursor = db.rawQuery(sql, null);
//打印表的所有列名
Log.i(TAG, Arrays.toString(cursor.getColumnNames()));
//打印当前数据库中的所有表
if (cursor.moveToFirst()) {
do {
String str = "";
for (String item : cursor.getColumnNames()) {
str += item + ": " + cursor.getString(cursor.getColumnIndex(item)) + "\n";
}
Log.i(TAG, str);
} while (cursor.moveToNext());
}
}
});
}
}
功能扩展
查看表是否存在
public Boolean tableIsExist(SQLiteDatabase db, String tableName){
boolean result = false;
Cursor cursor = null;
if(tableName == null){
return result;
}
String sql = "select count(*) from sqlite_master where type ='table' and name ='"+tableName.trim()+"'";
cursor = db.rawQuery(sql, null);
if(cursor.moveToNext()){
if(cursor.getInt(0) > 0){
result = true;
}
}
return result;
}
查看数据库中有哪些表
public ArrayList<String> tablesInDB(SQLiteDatabase db){
ArrayList<String> list = new ArrayList<String>();
String sql = "select name from sqlite_master where type='table'";
Cursor cursor = db.rawQuery(sql, null);
if (cursor.moveToFirst()) {
do {
list.add(cursor.getString(0));
} while (cursor.moveToNext());
}
return list;
}
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