import sys
from PyQt5.QtWidgets import QApplication,QDialog,QGridLayout,QMessageBox,QWidget,QVBoxLayout,QSpinBox,QTableWidget,QTableWidgetItem ,QTabWidget

class Dialog(QDialog):
    def __init__(self):
        QDialog.__init__(self)
        self.setWindowTitle("POS_DB")
        self.resize(800,600)
        self.layout=QGridLayout()
        self.setLayout(self.layout)

        self.tabs = QTabWidget()
        self.Server = QWidget()
        self.tabs.resize(650, 500)

        # Add tabs
        self.tabs.addTab(self.Server, "Server")
        self.tabs.addTab(self.Station, "Station")


           # Create Server tab
        self.Server.layout = QVBoxLayout(self)
        self.Servertable = QTableWidget()
        self.Server.layout.addWidget(self.Servertable)
        self.Server.setLayout(self.Server.layout)



        # Create Station tab
        self.Station.layout = QVBoxLayout(self)
        self.Stationtable = QTableWidget()
        self.Station.layout.addWidget(self.Stationtable)
        self.Station.setLayout(self.Station.layout)

        # Add tabs to widget
        self.layout.addWidget(self.tabs)
        self.setLayout(self.layout)

        self.db=QSqlDatabase.addDatabase('QMYSQL')
        self.db.setHostName("")
        self.db.setDatabaseName("")
        self.db.setUserName("")
        self.db.setPassword("")

    def Seleccionar(self):
        estado=self.db.open()
        if estado==False:
            QMessageBox.warning(self,"Error",self.db.lastError().text(),QMessageBox.Discard)
        else:
            #self.table.setColumnCount(4)
            self.table.setColumnCount(4)

            self.table.setHorizontalHeaderLabels(["Pid","Server_ip","Server_id","Server_Pwd"])
            row=0
            sql="select * from stt_server"
            query=QSqlQuery(sql)
            while query.next():
                self.table.insertRow(row)
                pid=QTableWidgetItem(str(query.value(0)))
                server_ip=QTableWidgetItem(str(query.value(1)))
                server_id=QTableWidgetItem(str(query.value(2)))
                server_pwd=QTableWidgetItem(str(query.value(3)))
                self.table.setItem(row,0,pid)
                self.table.setItem(row, 1, server_ip)
                self.table.setItem(row, 2, server_id)
                self.table.setItem(row, 3, server_pwd)
                row=row+1
        self.db.close()


app=QApplication(sys.argv)
dialogo=Dialog()
dialogo.show()
app.exec_()

Create Server tab에 테이블에 Seleccionar함수를 출력하고 싶습니다.