Question

如何使用命名查询在hibernate中获取当前数据库名称。

我试过这样，

String q1 = "select database()";
Query query1 = em.createQuery(q1);
String dbName = (String)query1.getResultList().get(0);
System.out.println("database name: "+dbName);

但这会抛出这样的错误，

HTTP ERROR 500

Problem accessing /admin/user. Reason:

    No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'database' {originalText=database}
    \-[EXPR_LIST] SqlNode: 'exprList'

Caused by:

java.lang.IllegalStateException: No data type for node: org.hibernate.hql.internal.ast.tree.MethodNode 
 \-[METHOD_CALL] MethodNode: '('
    +-[METHOD_NAME] IdentNode: 'database' {originalText=database}
    \-[EXPR_LIST] SqlNode: 'exprList'

但是，如果我在Sql GUI控制台中运行相同的查询，则会显示当前的数据库名称。

Answer 1

你可以试试这个

sessionFactory.getSettings().getConnectionProvider().getConnection().getMetaData().getURL();

Answer 2

请参见，查询使用的是postgres，在其他数据库方言中可能有所不同。我之所以使用，是因为我不确定是否已连接到正确的数据库。

在rs.getString（1）中：我写了“ 1”，因为postgres仅返回1列。如果结果没有给出数据库名称，则可以使用for并打印所有列（package com.mygdx.game.mytile; import com.badlogic.gdx.ApplicationAdapter; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.assets.AssetManager; import com.badlogic.gdx.graphics.GL20; import com.badlogic.gdx.graphics.OrthographicCamera; import com.badlogic.gdx.maps.MapProperties; import com.badlogic.gdx.maps.tiled.TiledMap; import com.badlogic.gdx.maps.tiled.TiledMapRenderer; import com.badlogic.gdx.maps.tiled.TmxMapLoader; import com.badlogic.gdx.maps.tiled.renderers.OrthogonalTiledMapRenderer; public class TileTest extends ApplicationAdapter { private TiledMap map; private TiledMapRenderer renderer; private OrthographicCamera camera; private AssetManager manager; private Integer tileWidth; private Integer tileHeight; private Integer mapWidthInTiles; private Integer mapHeightInTiles; private int mapWidthInPixels; private int mapHeightInPixels; @Override public void create () { manager = new AssetManager(); manager.setLoader(TiledMap.class, new TmxMapLoader()); manager.load("level_1_better.tmx", TiledMap.class); manager.finishLoading(); map = manager.get("level_1_better.tmx", TiledMap.class); MapProperties properties = map.getProperties(); tileWidth = properties.get("tilewidth", Integer.class); tileHeight = properties.get("tileheight", Integer.class); mapWidthInTiles = properties.get("width", Integer.class); mapHeightInTiles = properties.get("height", Integer.class); mapWidthInPixels = mapWidthInTiles * tileWidth; mapHeightInPixels = mapHeightInTiles * tileHeight; camera = new OrthographicCamera(320.f, 180.f); camera.position.x = mapWidthInPixels * .5f; camera.position.y = mapHeightInPixels * .35f; renderer = new OrthogonalTiledMapRenderer(map); } @Override public void render () { Gdx.gl.glClearColor(.5f, .7f, .9f, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); camera.update(); renderer.setView(camera); renderer.render(); } @Override public void dispose () { manager.dispose(); } }），不仅像我一样打印第1列。

for i=1 i<columnNumber; i++){print: rs.getString(i)}

在hibernate查询中获取数据库名称

2 个答案: