所以我有这个问题，真让我讨厌。我重写了扩展SQLiteOpenHelper的类的onCreate方法：
@Override
public void onCreate(SQLiteDatabase db) {
super.onCreate(db);
final String createAccTableCmd = ("CREATE TABLE IF NOT EXISTS " + ACCOUNTS_TABLE_NAME + " ( " +
ACCOUNT_KEY_ID + " INTEGER PRIMARY KEY ASC AUTOINCREMENT, " +
ACCOUNT_KEY_NAME + " TEXT UNIQUE ON CONFLICT IGNORE NOT NULL ON CONFLICT IGNORE, " +
ACCOUNT_KEY_SELECTED + " INTEGER NOT NULL ON CONFLICT IGNORE, " + //THIS IS IN MILLISECONDS
"CHECK (" + ACCOUNT_KEY_SELECTED + " = 0 OR " + ACCOUNT_KEY_SELECTED + " = 1) ON CONFLICT IGNORE" +
" ) ");
final String oneAndOnlyOneSelectedAccInsertTriggerCmd = "CREATE TRIGGER " + ONE_AND_ONLY_ONE_SELECTED_TRIGGER_INSERT_NAME + " " +
"AFTER INSERT ON " + ACCOUNTS_TABLE_NAME + " " +
"FOR EACH ROW " +
"BEGIN " +
"DELETE FROM " + ACCOUNTS_TABLE_NAME + " WHERE " + ACCOUNT_KEY_ID + " = NEW." + ACCOUNT_KEY_ID + "; " +
"END";
final String oneAndOnlyOneSelectedUpdateTriggerCmd = "CREATE TRIGGER " + ONE_AND_ONLY_ONE_SELECTED_TRIGGER_UPDATE_NAME + " " +
"AFTER UPDATE ON " + ACCOUNTS_TABLE_NAME + " " +
"FOR EACH ROW " +
"WHEN (SELECT(SUM(" + ACCOUNT_KEY_ID + ")) <> 1) " +
"BEGIN " +
"UPDATE " + ACCOUNTS_TABLE_NAME + " SET " + ACCOUNT_KEY_SELECTED + " = 0; " +
"UPDATE " + ACCOUNTS_TABLE_NAME + " SET " + ACCOUNT_KEY_SELECTED + " = 1 WHERE " + ACCOUNT_KEY_ID + " = NEW." + ACCOUNT_KEY_ID + "; " +
"END";
synchronized (DB_LOCK) {
db.beginTransaction();
db.execSQL(createAccTableCmd);
db.execSQL(oneAndOnlyOneSelectedAccInsertTriggerCmd);
db.execSQL(oneAndOnlyOneSelectedUpdateTriggerCmd);
addTableName(ACCOUNTS_TABLE_NAME);
ContentValues cv = new ContentValues();
cv.put(ACCOUNT_KEY_ID, 0);
cv.put(ACCOUNT_KEY_NAME, "name");
cv.put(ACCOUNT_KEY_SELECTED, 0);
Log.d("debug", "-1 if error on insert: " + db.insert(ACCOUNTS_TABLE_NAME, "", cv));
Log.d("debug", "Size: " + db.query(ACCOUNTS_TABLE_NAME, null, null, null, null, null, ACCOUNT_KEY_ID + " ASC").getCount());
db.setTransactionSuccessful();
db.endTransaction();
LBackupAgent.requestBackup(mContext);
}
Log.d("debug", "Size after ending the transaction: " + db.query(ACCOUNTS_TABLE_NAME, null, null, null, null, null, ACCOUNT_KEY_ID + " ASC").getCount());
}
可以预期的结果是：
-1如果插入错误：0
大小：0 / *或1，如果选择考虑了当前事务未提交的数据，则我不确定* /
结束交易后的大小：1
当实际输出恰好是：
-1如果插入错误：0
大小：0
结束交易后的大小：0
如何成功插入但选择返回0行？
我已经检查了外壳是否存在该表，但实际上它是空的，这可以用以下事实来解释：在onCreate（）完成之前，该表似乎并不存在，并证明了由0返回的0插入命令。我是否应该猜测这种设计约束，以确保onCreate仅包含CREATE TABLE，CREATE TRIGGER和此类语句？如果我认为我的模式定义需要插入（情况如此）怎么办？
最佳答案
尝试插入一些虚拟值，而不是下面的内容：
ContentValues defaultAcc = mapAccountToStorable(defaultAccDataModel = new AccountListRecyclerAdapter.AccountDataModel(
LBudgetUtils.getInt(mContext, "default_account_id"),
LBudgetUtils
.getString(mContext, "default_account_name"),
mContext.getResources().getBoolean(
R.bool.default_account_selected)));
而不是将nullColumnHack发送为null，而是将其发送为“”。即使值是null，也将确保在表中创建一行。
db.insert(ACCOUNTS_TABLE_NAME, "", defaultAcc)
请尝试以下方法：
db.beginTransaction();
db.execSQL(createAccTableCmd);
db.execSQL(oneAndOnlyOneSelectedAccInsertTriggerCmd);
db.execSQL(oneAndOnlyOneSelectedUpdateTriggerCmd);
db.setTransactionSuccessful();
db.endTransaction();
db.beginTransaction();
addTableName(ACCOUNTS_TABLE_NAME);
AccountListRecyclerAdapter.AccountDataModel defaultAccDataModel;
ContentValues defaultAcc = mapAccountToStorable(defaultAccDataModel = new AccountListRecyclerAdapter.AccountDataModel(LBudgetUtils.getInt(mContext, "default_account_id"), LBudgetUtils.getString(mContext, "default_account_name"), mContext.getResources().getBoolean(R.bool.default_account_selected)));
Log.d("debug", "-1 if error on insert: " + db.insert(ACCOUNTS_TABLE_NAME, null, defaultAcc));
db.setTransactionSuccessful();
db.endTransaction();
Log.d("debug", "Size: " + db.query(ACCOUNTS_TABLE_NAME, null, null, null, null, null, ACCOUNT_KEY_ID + " ASC").getCount());
关于java - 如预期那样调用onCreate。但是没有创建表，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/25443680/