Android Question JdbcResultSet get value from specific cell

[Kasun Kanchana]

Hi. I'm using Jdbc as remote MySQL connector. Assume that I want to get the value of 4th row 2nd column (as below image), How to do it?

In SQL we have rowcount and position option. But in Jdbc, I don't know how to get the value from specific cell. Do I have to filter the data from SQL query like SELECT * FROM products WHERE product_name='"product name"' ?

PS; I used SQL query to filter data. but it gives error.

This is my code. I used Grid module from scsjc

Sub grid_ItemClick (index As Int, Value As Object)
    Log("value:" & Value)
    Log("index:" & index )
    Dim Cursor As JdbcResultSet
    Cursor = connection.mysql.ExecQuery("SELECT * FROM products WHERE id='"&index&"'")
    Log(Cursor.GetString("product_name"))
End Sub

Error
Error occurred on line: 88 (menu)
java.sql.SQLException: Before start of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:996)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:935)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:924)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:870)
at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:781)
at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5239)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5162)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5201)
at anywheresoftware.b4j.objects.SQL$ResultSetWrapper.GetString(SQL.java:523)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:180)
at anywheresoftware.b4a.debug.Debug.delegate(Debug.java:262)
at b4a.example.menu._grid_itemclick(menu.java:873)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.debug.Debug.CallSub4(Debug.java:318)
at anywheresoftware.b4a.debug.Debug.CallSubNew3(Debug.java:288)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.keywords.Common.CallSubDebug3(Common.java:1061)
at b4a.example.grid._panel_click(grid.java:459)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:176)
at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
at android.view.View.performClick(View.java:6659)
at android.view.View.performClickInternal(View.java:6631)
at android.view.View.access$3100(View.java:790)
at android.view.View$PerformClick.run(View.java:26187)
at android.os.Handler.handleCallback(Handler.java:907)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:216)
at android.app.ActivityThread.main(ActivityThread.java:7625)

 

[Kasun Kanchana]

I found the solution.
have to use,

Do While Cursor.NextRow
    Log(Cursor.GetString("product_name"))
Loop

But if anyone know how to get value from specific cell without doing all this, Please let me know

 

[Erel]

This is really broken code:

Cursor = connection.mysql.ExecQuery("SELECT * FROM products WHERE id='"&index&"'")

[B4X] "Code Smells" - common mistakes and other tips

You are not closing the result set.

But if anyone know how to get value from specific cell without doing all this, Please let me know

You can change the query to return a single result and use ExecQuerySingleResult2.