java判断数据库是否存在的代码：

public static boolean isExistDatabase(String database) {        Connection conn = null;        Statement stmt = null;        ResultSet rs = null;// 数据库结果集        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关闭连接失败：" + e.getMessage(), Status.INTERNAL_SERVER_ERROR);            }        }    }

关键SQL语法：

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