Creating table dynamically (On Button Click) In Android

Question

I am writing an application and it needs tables to be created dynamically. I've written the following code :

public void CreateDynamicTables(String Table_Name, String Contact_ID, String Display_Name){
        dbs.execSQL("DROP TABLE IF EXISTS " + Table_Name);
        String query = "CREATE TABLE " + Table_Name + "(" + CID + " TEXT PRIMARY KEY, " + DName + " TEXT);";
        dbs.execSQL(query);
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(CID, Contact_ID);
        cv.put(DName, Display_Name);
        db.insert(Table_Name, null, cv);
        db.close();
    }

But it crashes the application. Cannot find whats wrong with it.

Logcat:

Logcat

line 62 : dbs.execSQL("DROP TABLE IF EXISTS " + Table_Name); — Priyabrata
– Priyabrata, Commented Feb 27, 2014 at 12:35
Did you initialize dbs anywhere? It's not in the code provided... — Melquiades
– Melquiades, Commented Feb 27, 2014 at 12:39

MDMalik · Accepted Answer · 2014-02-27 12:31:06Z

2

At some places you were using db at some places dbs

Try this code

public void CreateDynamicTables(String Table_Name, String Contact_ID, String Display_Name)       
{

       dbs = this.getWritableDatabase();
        dbs.execSQL("DROP TABLE IF EXISTS " + Table_Name);
        String query = "CREATE TABLE " + Table_Name + "(" + CID + " TEXT PRIMARY KEY, " + DName + " TEXT);";
        dbs.execSQL(query);
        dbs = this.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(CID, Contact_ID);
        cv.put(DName, Display_Name);
        dbs.insert(Table_Name, null, cv);
        dbs.close();
    }

answered Feb 27, 2014 at 12:31

MDMalik

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4 Comments

Priyabrata Over a year ago

I used dbs(global variable) to to create the table and db(local) to insert data in the table. However, changing db to dbs, didn't help and results in the same error.

MDMalik Over a year ago

@Priyabrata try Log.i and find till which step does it executes.. Will be easier to help you out

Priyabrata Over a year ago

It executes the first line and crashes. i.e DROP TABLE IF EXISTS line

MDMalik Over a year ago

do u have this code dbs = this.getWritableDatabase();

Melquiades · Accepted Answer · 2014-02-27 12:41:44Z

2

If NullPointerException happens - as you say - on line:

dbs.execSQL("DROP TABLE IF EXISTS " + Table_Name);

then most likely your dbs is not initialized. Initialize it before using with:

dbs = getWritableDatabase();

Also, check if Table_Name is not null too.

answered Feb 27, 2014 at 12:41

Melquiades

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1 Comment

Priyabrata Over a year ago

Spot on!! That Worked!!

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