Question

当我尝试检查列是否存在时，它会破坏应用程序并显示以下错误：

Caused by: android.database.sqlite.SQLiteException: no such column: perfumes (code 1): , while compiling: SELECT * FROM savedproducts WHERE pid = 1 AND ptype = perfumes
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1113)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:690)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:59)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1438)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1377)
at app.botikaty.com.DatabaseHandler.CheckIfExist(DatabaseHandler.java:137)
at app.botikaty.com.ViewProductActivity.onCreate(ViewProductActivity.java:80)

我尝试过的是这段代码（DatabaseHandler.java:137）：

 int CheckIfExist(String id,String type) {
        String countQuery = "SELECT * FROM " + TABLE_CONTACTS + " WHERE pid = " + id + " AND ptype = " + type;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        return cursor.getCount();
    }

ViewProductActivity.java:80

int issaved = dbHandler.CheckIfExist(theproductid,theproducttype);
            if (issaved != -1){
                savebtn.setLiked(true);
            }else{
                savebtn.setLiked(false);
            }

我希望问题清楚明白，可以做什么？

我使用的一些文件：

DatabaseHandler.java - ＆gt; https://pastebin.com/94pkJFLd

Contact.java - ＆gt; https://pastebin.com/P8DiHbxY

Answer 1

您需要将其更改为：

 String countQuery = "SELECT * FROM " + TABLE_CONTACTS + " WHERE pid = " + id + " AND ptype = '" + type+"'";

这只是在您的类型字符串周围加上单引号，表示它是数据库的字符串值

所以查询将如下所示： SELECT * FROM savedproducts WHERE pid = 1 AND ptype ='perfumes'

实际查询中的差异是ptype = perfumes vs ptype ='perfumes'

你没有在你的类型字符串周围放置单引号，所以数据库认为你试图获取一个列，而实际上是在试图告诉它ptype的值

检查列是否存在

1 个答案: