java判斷數據庫是否存在的代碼：

public static boolean isExistDatabase(String database) {         Connection conn = null;         Statement stmt = null;         ResultSet rs = null;// 數據庫結果集         try {             conn = getConnection();             stmt = conn.createStatement();             String sql = "SELECT COUNT(*) FROM information_schema.schemata WHERE schema_name="" + database + """;             System.out.println(sql);             rs = stmt.executeQuery(sql);             if (rs.next()) {                 if (rs.getInt(1) == 0) {                     return false;                 } else {                     return true;                 }             }             return false;         } catch (Exception e) {             throw new TenantException(e.getMessage(), Status.INTERNAL_SERVER_ERROR);         } finally {             try {                 if (rs != null) {                     rs.close();                 }                 if (stmt != null) {                     stmt.close();                 }                 if (conn != null) {                     conn.close();                 }             } catch (SQLException e) {                 throw new TenantException("mysql關閉連接失敗：" + e.getMessage(), Status.INTERNAL_SERVER_ERROR);             }         }     }

關鍵SQL語法：

String sql = "SELECT COUNT(*) FROM information_schema.schemata WHERE schema_name="" + database + """;