Android Question [Solved] How to use MySQL LIMIT clause in jRDC2?

Sergio Castellari

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Situation:
a) I need to make the following query:

B4X: 
sql.select_articulos_precios=Select a.CODIGO, a.CODIFICADO, a.NOMBRE, a.PVENTA, a.PVENTA_2, a.PVENTA_3, a.PVENTA_4, a.PVENTA_5, a.DOLARIZADO From ARTICULO a \
                              Donde a.FECHAEGRE = "0000-00-00" y Substr (a.NOMBRE, 1,?) =? ordenar por un.NOMBRE Limite 0,?

But when using it, it throws the following error:
<pre> com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near &apos;&apos;300&apos;&apos; at line 1</pre></p><hr><a href="http://eclipse.org/jetty">Powered by Jetty:// 9.4.z-SNAPSHOT</a><hr/>

I use 300 as a limit.
If I do the same query from MySQL Query Browse, it works fine.

What can I be doing wrong in the query inside "config.properties"
Greetings[/CODE]
 
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TILogistic

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??

Donde a.FECHAEGRE = "0000-00-00" y Substr (a.NOMBRE, 1,?) =? ordenar por un.NOMBRE Limite 0,?
Click to expand...

Select instruction is in Spanish.

???
 
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Sergio Castellari

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Erel said:
It should be LIMIT, not limite.
Click to expand...
Chrome translated it automatically. But it really is "LIMIT" as I intended to use it.
Anyway:
a) LIMIT ?
b) LIMIT 0,?
c) LIMIT = ?

None of them work.
It only works if you put a FIXED value, for example:
LIMIT 250 o LIMIT 0,250
 
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Sergio Castellari

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Hi @OliverA,
Thank you for your concern.
In the file "config.Properties" I have the following SQL statement:

B4X: 
#####################
# ARTICULOS y STOCK #
#####################
#Consulta ARTICULOS (lista de Precios)
sql.select_articulos_precios_asterix=Select a.CODIGO, a.CODIFICADO, a.NOMBRE, a.PVENTA, a.PVENTA_2, a.PVENTA_3, a.PVENTA_4, a.PVENTA_5, a.DOLARIZADO From ARTICULO a \
                              Where a.FECHAEGRE="0000-00-00" and (a.CODPROV>=? and a.CODPROV<=?) and (a.LINEA>=? and a.LINEA<=?) and \
                              (a.RUBRO>=? and a.RUBRO<=?) order by a.NOMBRE Limit 5000
sql.select_articulos_precios_filtrada=Select a.CODIGO, a.CODIFICADO, a.NOMBRE, a.PVENTA, a.PVENTA_2, a.PVENTA_3, a.PVENTA_4, a.PVENTA_5, a.DOLARIZADO From ARTICULO a \
                              Where a.FECHAEGRE="0000-00-00" and Substr(a.NOMBRE,1,?)=? and (a.CODPROV>=? and a.CODPROV<=?) and (a.LINEA>=? and a.LINEA<=?) and \
                              (a.RUBRO>=? and a.RUBRO<=?) order by a.NOMBRE Limit 250
sql.select_articulos_precios_vacia=Select a.CODIGO, a.CODIFICADO, a.NOMBRE, a.PVENTA, a.PVENTA_2, a.PVENTA_3, a.PVENTA_4, a.PVENTA_5, a.DOLARIZADO From ARTICULO a \
                              Where a.FECHAEGRE="0000-00-00" and (a.CODPROV>=? and a.CODPROV<=?) and (a.LINEA>=? and a.LINEA<=?) and \
                              (a.RUBRO>=? and a.RUBRO<=?) order by a.NOMBRE Limit 250

From the APP B4A, I call it as follows:

B4X: 
'+++ BUSCAR Articulos ++++
Private Sub btnArticulo_Click
    IME1.HideKeyboard
    Dim aRegistros, aCampos                                        As List
    Dim aCom()                                                                As String
    Dim MinPro = "00000", MaxPro = "99999"        As String
    Dim MinLin = "000", MaxLin = "999"                As String
    Dim MinRub = "000", MaxRub = "999"                As String
    Dim prove = lblProv.Text.SubString2(0,5)     As String
    Dim linea = lblLinea.Text.SubString2(0,3) As String
    Dim rubro = lblRubro.Text.SubString2(0,3) As String
    Dim nCar = 0                                                             As Int
    Dim cFiltro = edtArticulo.Text                         As String
    nCar = cFiltro.Length
'    If nCar = 0 Then
'        Main.beepError.Beep : edtArticulo.RequestFocus : Return
'    End If
    If prove <> "00000" Then                    'Verifico si filtro PROVEDOR
        MinPro=prove : MaxPro=prove
    End If
    If linea <> "000" Then                        'Verifico si filtro LINEA
        MinLin=linea : MaxLin=linea
    End If
    If rubro <> "000" Then                        'Verifico si filtro RUBRO
        MinRub=rubro : MaxRub=rubro
    End If
    ProgressDialogShow("Buscando Articulos...ESPERE...")
    aRegistros.Initialize
    aCampos.Initialize
    If cFiltro <> "*" And cFiltro <> "" Then
        'Trae los primeros 250 registros o menos (segun filtro elegido)
        aCom = Array As String(nCar,cFiltro,MinPro,MaxPro,MinLin,MaxLin,MinRub,MaxRub)
        Wait For (Main.jConex.GetRecord("select_articulos_precios_filtrada", aCom)) Complete (Respuesta As Map)
    Else If cFiltro = "*" Then
        'Trae los primeros 5000 registros o menos (segun filtro elegido)
        aCom = Array As String(MinPro,MaxPro,MinLin,MaxLin,MinRub,MaxRub)
        Wait For (Main.jConex.GetRecord("select_articulos_precios_asterix", aCom)) Complete (Respuesta As Map)
    Else
        'Trae los primeros 250 registros o menos (segun filtro elegido)  Boton Re-Inicio
        aCom = Array As String(MinPro,MaxPro,MinLin,MaxLin,MinRub,MaxRub)
        Wait For (Main.jConex.GetRecord("select_articulos_precios_vacia", aCom)) Complete (Respuesta As Map)
    End If
    If Respuesta.Get("Correcto") Then
        Dim rs     As DBResult
        Dim cCod,cDes,cPre1,cPre2,cPre3,cPre4,cPre5,cDol As String
        rs = Respuesta.Get("Datos")
        Dim Lista As List = rs.Rows
        Dim nLineas = Lista.Size, nVez=0 As Int
        Log("Registros totales Articulos: " & nLineas)
    For Each row() As Object In rs.Rows
            cCod = row(0) & Chr(13) & row(1)
            cDes = row(2)
            cPre1 = row(3)
            cPre2 = row(4)
            cPre3 = row(5)
            cPre4 = row(6)
            cPre5 = row(7)
            cDol = row(8)
            If cDol = "T" Then cDes = "[u$s] " & cDes
            aCampos.Initialize
            aCampos.Add(cCod)
            aCampos.Add(cDes)
            aCampos.Add(cPre1)
            aCampos.Add(cPre2)
            aCampos.Add(cPre3)
            aCampos.Add(cPre4)
            aCampos.Add(cPre5)
            aRegistros.Add(aCampos)
        Next
        B4XTable1.SetData(aRegistros)                                     
        SeteoColumna("Cod", "CENTER", "LEFT",0,-1,-1)
        SeteoColumna("Descripción", "CENTER", "LEFT",0,-1,-1)
        SeteoColumna("Vta1", "CENTER", "RIGHT",2,2,-1)
        SeteoColumna("Vta2", "CENTER", "RIGHT",2,2,-1)
        SeteoColumna("Vta3", "CENTER", "RIGHT",2,2,-1)
        SeteoColumna("Vta4", "CENTER", "RIGHT",2,2,-1)
        SeteoColumna("Vta5", "CENTER", "RIGHT",2,2,-1)
        B4XTable1.Refresh
        ProgressDialogHide
    Else
        ProgressDialogHide
         MsgboxAsync(Respuesta.Get("Mensaje"),"")
        Return
    End If
End Sub

When I use the "LIMIT" clause with a FIXED value, IT WORKS. But if I try to use it with values sent from the APP, it gives ERROR.
I have tried the three ways described above, but none of them work.
Maybe there is a different syntax to do it from jRDC2.
From the windows application "MySQL Query Brows" it works correctly.

However, I decided to use FIXED values (as shown in the code) and that way it works CORRECTLY.

A big virtual hug!

NOTE: By the way, every day I am more in love with B4X. As I learn more, I am impressed by the power, flexibility and speed of operation.
 
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OliverA

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You're still not showing all the code on how you call the jRDC2 statement with the limit as one of your properties that you sent to the server. I need to see how you use the LIMIT statement with the ? in the statement. How you call it (the statement with LIMIT ? or LIMIT ?, ?) from your program.
 
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Sergio Castellari

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Try these three ways:
a) LIMIT ?
b) LIMIT 0,?
c) LIMIT = ?

None worked. They give the error of the initial post.
That is why I show in the previous post, the call and the SQL statements, with "LIMIT" and a fixed value.
 
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OliverA

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Sergio Castellari said:
None worked. They give the error of the initial post.
Click to expand...
How do you pass the parameters? String array? Object Array? Is the Limit you sent a String? A Int? I need to see how you call the statement from your client program. You have not shown me that yet.
 
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Sergio Castellari

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I was sending it as "INT"

B4X: 
    Dim aRegistros, aCampos    As List
    Dim aCom() As String
    Dim nLimit = 250 As Int
    Dim MinPro = "00000", MaxPro = "99999" As String
    Dim MinLin = "000", MaxLin = "999" As String
    Dim MinRub = "000", MaxRub = "999" As String
    Dim prove = lblProv.Text.SubString2(0,5) As String
    Dim linea = lblLinea.Text.SubString2(0,3) As String
    Dim rubro = lblRubro.Text.SubString2(0,3) As String
    Dim nCar = 0 As Int
    Dim cFiltro = edtArticulo.Text As String
    nCar = cFiltro.Length
    If prove <> "00000" Then                    'Verifico si filtro PROVEDOR
        MinPro=prove : MaxPro=prove
    End If
    If linea <> "000" Then                        'Verifico si filtro LINEA
        MinLin=linea : MaxLin=linea
    End If
    If rubro <> "000" Then                        'Verifico si filtro RUBRO
        MinRub=rubro : MaxRub=rubro
    End If
    ProgressDialogShow("Buscando Articulos...ESPERE...")
    aRegistros.Initialize
    aCampos.Initialize
    If cFiltro <> "*" And cFiltro <> "" Then
        'Trae los primeros 250 registros o menos (segun filtro elegido)
        aCom = Array As String(nCar,cFiltro,MinPro,MaxPro,MinLin,MaxLin,MinRub,MaxRub, nLimit)
        Wait For (Main.jConex.GetRecord("select_articulos_precios_filtrada", aCom)) Complete (Respuesta As Map)
        ...
 
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OliverA

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No, you are not. Since you are creating an Array As String, your nLimit is converted to a string. Try
B4X: 
...
Dim aCom() As Object
...
aCom = Array (nCar,cFiltro,MinPro,MaxPro,MinLin,MaxLin,MinRub,MaxRub, nLimit)
...
Note: You need to change your GetRecord to accept an object array instead of a string array
 
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Sergio Castellari

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And at this point, wouldn't it be easier to pass "nLimit" to a string?
NOTE: I have no idea how to take a numeric variable to a string variable ...
 
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OliverA

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Sergio Castellari said:
And at this point, wouldn't it be easier to pass "nLimit" to a string?
Click to expand...
No. The whole issue is that nLimit is sent to jRDC2 as a string. Internally (in the Java code), the parameterized query code in B4J uses getObject to determine what a parameter is. If it is a string, it keeps it as a string. But Limit does not need a string, it needs a number. If you look at the sample code provided in the jRDC2 post (https://www.b4x.com/android/forum/t...-rdc-remote-database-connector.61801/#content), parameters are passed as an object array, not a string array.
Sergio Castellari said:
NOTE: I have no idea how to take a numeric variable to a string variable ...
Click to expand...
The whole goal is to not convert the numeric variable to a string. By making it part of a String Array (in your code aCom is a string array), the B4X language converts your numeric value to a String.
 
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Sergio Castellari

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AHA. Now I am getting it.
But the thing is, I have a jRDC2 Multi (created by Erel)
https://www.b4x.com/android/forum/threads/mysql-connector-for-b4i.116617/#post-729095
which is edited for multiple databases:
APP side:

B4X: 
Sub CreateRequest As DBRequestManager
    'Por cada solicitud, se crea un nuevo DBRequest...
  Dim Req As DBRequestManager
  Req.Initialize(Me, rdcLink & "?DBName=" & Main.pDBName )   'Aqui va la DBName a utilizar!!!
  Return Req
End Sub

Sub CreateCommand(Name As String, Parameters() As Object) As DBCommand
   Dim cmd As DBCommand
   cmd.Initialize
   cmd.Name = Name
   If Parameters <> Null Then cmd.Parameters = Parameters
   Return cmd
End Sub

Public Sub GetRecord (Command As String, parameters() As String) As ResumableSub
    Dim Respuesta As Map
    Respuesta.Initialize
    Dim req As DBRequestManager = CreateRequest
    Dim cmd As DBCommand = CreateCommand(Command, parameters)
    Log("conectando al servidor...espere...")
    Wait For (req.ExecuteQuery(cmd, 0, Null)) JobDone(j As HttpJob)
    Respuesta.Put("Correcto",j.Success)
    If j.Success Then
        req.HandleJobAsync(j, "req")
        Wait For (req) req_Result(Res As DBResult)
      Respuesta.Put("Mensaje","Datos obtenidos")
        'req.PrintTable(Res)
    Else
      Respuesta.Put("Mensaje","ERROR !!!. Servidor de datos NO disponible. Vuelva a intentarlo nuevamente...")
        Log("ERROR: " & j.ErrorMessage)
    End If
    j.Release
    Respuesta.Put("Datos",Res)
    Return Respuesta
End Sub

JRDC2 Server Side:

B4X: 
Sub AppStart (Args() As String)
    srvr.Initialize("")
    Connectors = srvr.CreateThreadSafeMap
    Dim dbs As List = Array("gest","pepe","guapa") 'read from a file
    For Each db As String In dbs
        Dim con As RDCConnector
        con.Initialize(db)
        Connectors.Put(db, con)
    Next
    srvr.Port = 17101
    srvr.AddHandler("/test", "TestHandler", False)
    srvr.AddHandler("/rdc", "RDCHandler", False)
    srvr.Start
    Log($"jRDC is running (version = $1.2{VERSION})"$)
    StartMessageLoop
End Sub

The problem is that I have no idea how to adapt or create a new "GetRecord" for these cases.
 
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TILogistic

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GetRecord (Command As String, parameters() As String) As ResumableSub

to

GetRecord (Command As String, parameters() As Object) As ResumableSub

see:
B4X: 
Sub CreateCommand(Name As String, Parameters() As Object) As DBCommand
   Dim cmd As DBCommand
   cmd.Initialize
   cmd.Name = Name
   If Parameters <> Null Then cmd.Parameters = Parameters
   Return cmd
End Sub
 
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OliverA

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B4X: 
Public Sub GetRecord (Command As String, parameters() As String) As ResumableSub
Change to
B4X: 
Public Sub GetRecord (Command As String, parameters() As Object) As ResumableSub
Nija’d by a few seconds
 
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TILogistic

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see:
Important

LIMIT N1
or
LIMIT N1, N2

N1 Offset
N2 Row

ref:

MySQL LIMIT

In this tutorial, you will learn how to use MySQL LIMIT clause to constrain the number of rows returned by the SELECT statement.
www.mysqltutorial.org
 
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TILogistic

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Write the SQL statement in this way, to understand it.

SQL: 
sql.select_articulos_precios_filtrada = SELECT a.CODIGO \
                                             , a.CODIFICADO \
                                             , a.NOMBRE \
                                             , a.PVENTA \
                                             , a.PVENTA_2 \
                                             , a.PVENTA_3 \
                                             , a.PVENTA_4 \
                                             , a.PVENTA_5 \
                                             , a.DOLARIZADO  \
                                          FROM ARTICULO a \
                                         WHERE a.FECHAEGRE = "0000-00-00"  \
                                           AND SUBSTR(a.NOMBRE, 1, ?) = ? \
                                           AND (a.CODPROV >= ? AND a.CODPROV <= ?)  \
                                           AND (a.LINEA >= ? AND a.LINEA <= ?)  \
                                           AND (a.RUBRO >= ? AND a.RUBRO <= ?)  \
                                         ORDER BY a.NOMBRE \
                                         LIMIT ?
???
 
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