Question

如何在查询的（？）字符串中连接？或％s喜欢php ...我知道用+做但不是这样！我需要查询像PHP一样更改字符串值吗？或％s（类似于Android Java）......

variableRange = ActiveSheet.Range("M1").Value

项目中所有模型的dbConnection层（Project中的所有模型都扩展了此类（通用））

package yyy.yyy.yyy.yyy.actions;

import android.content.Context;

import yyy.yyy.yyy.yyy.models.CategoriesModel;

public class CategoriesActions extends CategoriesModel {
    protected String sqlInsert = "INSERT INTO categories (title) VALUES (?) ";
    protected String sqlUpdate = "UPDATE categories SET title=? WHERE id=?";
    protected String sqlDelete = "UPDATE FROM categories WHERE id=?";
    protected String sqlSelect = "SELECT %s FROM categories %s %s %s"; // ? or %s

    public CategoriesActions(Context context) {
        super(context);
    }

    public boolean insert()
    {
        String cat_title = this.getTitle();
        String sql = sqlInsert; // <---------- need concatenate cat_title in sqlInser (?)

        //return sql;
        return this.RunQuery(sql);
    }

    public String update()
    {
        String sql = "";
        return sql;
    }

    public String delete()
    {
        String sql = "";
        return sql;
    }

    public String select(String columns, String where, String order, String limit)
    {
        String sql = "";
        return sql;
    }
}

模型层（扩展dbConnection类（通用）

package yyy.yyy.yyy.yyy.database;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class dbConnection extends SQLiteOpenHelper {
    private SQLiteDatabase conn;

    public static final String DATABASE_NAME="App.Xitano";
    private static final int DATABASE_VERSION = 1;

    private static final String TABLE_CATEGORIES = "categories";
    private static final String TABLE_PAYMENT_TYPES = "payment_types";
    private static final String TABLE_TRANSACTIONS = "transactions";

    private static final String CATEGORIES_KEY_ID = "id";
    private static final String CATEGORIES_KEY_TITLE = "title";
    private static final String CATEGORIES_KEY_CREATED_AT = "created_at";
    private static final String CATEGORIES_KEY_UPDATED_AT = "updated_at";

    private static final String PAYMENT_TYPES_KEY_ID = "id";
    private static final String PAYMENT_TYPES_KEY_TITLE = "title";
    private static final String PAYMENT_TYPES_KEY_CREATED_AT = "created_at";
    private static final String PAYMENT_TYPES_KEY_UPDATED_AT = "updated_at";

    private static final String TRANSACTIONS_KEY_ID = "id";
    private static final String TRANSACTIONS_KEY_IN_OUT = "in_out";
    private static final String TRANSACTIONS_KEY_CATEGORIES_ID = "categories_id";
    private static final String TRANSACTIONS_KEY_PAYMENT_TYPES_ID = "payment_types_id";
    private static final String TRANSACTIONS_KEY_TITLE = "title";
    private static final String TRANSACTIONS_KEY_AMOUNT = "amount";
    private static final String CTRANSACTIONS_KEY_CREATED_AT = "created_at";
    private static final String TRANSACTIONS_KEY_UPDATED_AT = "updated_at";

    private static final String CREATE_TABLE_CATEGORIES = "CREATE TABLE " + TABLE_PAYMENT_TYPES + "("
            + PAYMENT_TYPES_KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + PAYMENT_TYPES_KEY_TITLE + " TEXT,"
            + PAYMENT_TYPES_KEY_CREATED_AT + "TIMESTAMP,"
            + PAYMENT_TYPES_KEY_UPDATED_AT + "TIMESTAMP );";

    private static final String CREATE_TABLE_PAYMENT_TYPES = "CREATE TABLE " + TABLE_CATEGORIES + "("
            + CATEGORIES_KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + CATEGORIES_KEY_TITLE + " TEXT,"
            + CATEGORIES_KEY_CREATED_AT + "TIMESTAMP,"
            + CATEGORIES_KEY_UPDATED_AT + "TIMESTAMP );";

    public dbConnection(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        Log.d("table", TABLE_CATEGORIES);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        /*
        db.execSQL(CREATE_TABLE_STUDENTS);
        db.execSQL(CREATE_TABLE_USER_HOBBY);
        db.execSQL(CREATE_TABLE_USER_CITY);
        */
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        /*
        db.execSQL("DROP TABLE IF EXISTS '" + TABLE_USER + "'");
        db.execSQL("DROP TABLE IF EXISTS '" + TABLE_USER_HOBBY + "'");
        db.execSQL("DROP TABLE IF EXISTS '" + TABLE_USER_CITY + "'");
        onCreate(db);
        */
    }

    public SQLiteDatabase ConnectWritable(){
        this.conn = this.getWritableDatabase();
        return this.conn;
    }

    public SQLiteDatabase ConnectReadable(){
        this.conn = this.getReadableDatabase();
        return this.conn;
    }

    public boolean RunQuery(String sql){
        SQLiteDatabase stm = this.ConnectWritable();
        stm.execSQL(sql);
        return true;
    }

    public Cursor RunSelect(String sql){
        SQLiteDatabase stm = this.ConnectReadable();
        Cursor cursor = stm.rawQuery(sql, null);
        return cursor;
    }

    public int RunCount(String sql){
        SQLiteDatabase stm = this.ConnectReadable();
        Cursor cursor = stm.rawQuery(sql, null);
        cursor.moveToFirst();
        if (cursor.getCount() > 0 && cursor.getColumnCount() > 0) {
            cursor.close();
            return cursor.getInt(0);
        } else {
            cursor.close();
            return 0;
        }
    }

    public void Disconnect(){
        this.conn.close();
        this.conn = null;
    }
}

谢谢你！

Answer 1

你提到准备好的陈述“在这一层并不好”，但质疑为什么准备好的陈述对你不起作用？例如，在您的代码中，您有：

protected String sqlInsert = "INSERT INTO categories (title) VALUES (?) ";

您可以轻松创建预备声明：

PreparedStatement pstmt = con.prepareStatement(sqlInsert);

然后，您所要做的就是使用可用于预准备语句的set（）方法将相关参数传递给查询。更多信息here。

Answer 2

解决：

protected String sqlInsert = "INSERT INTO categories (title) VALUES (%s) ";
public boolean insert()
{
    String sql = String.format(sqlInsert, this.getTitle());
    return this.RunQuery(sql);
}

谢谢你，朋友们！

声明变量后的Android Java查询字符串动态值

2 个答案: