如何使用查询来执行以下操作:
(SELECT count(*) from table WHERE user = "root" and date(dt) = NOW())
( (SELECT count(*) from table WHERE user = "root" and field1 = "" and date(dt) = NOW()))
SQL 表
-- phpMyAdmin SQL Dump
-- version 5.0.2
-- https://www.phpmyadmin.net/
--
-- Host: 127.0.0.1:3306
-- Tempo de geração: 16-Abr-2021 às 23:17
-- Versão do servidor: 5.7.31
-- versão do PHP: 7.3.21
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
START TRANSACTION;
SET time_zone = "+00:00";
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8mb4 */;
--
-- Banco de dados: `db_test`
--
-- --------------------------------------------------------
--
-- Estrutura da tabela `tbl`
--
DROP TABLE IF EXISTS `tbl`;
CREATE TABLE IF NOT EXISTS `tbl` (
`user` varchar(255) NOT NULL,
`field1` varchar(255) NOT NULL,
`dt` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
--
-- Extraindo dados da tabela `tbl`
--
INSERT INTO `tbl` (`user`, `field1`, `dt`) VALUES
('root', 'not empty', '2021-04-17 00:17:27'),
('root', '', '2021-04-17 00:17:27');
COMMIT;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
示例表
+------+-----------+
| user | field1 |
+------+-----------+
| root | not empty |
| root | |
+------+-----------+
预期输出
+------+-------------------------------------+
| user | perc_register_that_have_empty_field |
+------+-------------------------------------+
| root | 50 |
+------+-------------------------------------+
答案 0 :(得分:0)
你可以计算一个表达式。例如:
SELECT
sum(case when field1 = '' or field1 is null then 1 else 0 end) /
count(*) as perc_register_that_have_empty_field
from t
WHERE user = 'root' and date(dt) = curdate()
结果:
perc_register_that_have_empty_field
-----------------------------------
0.4000
请参阅 DB Fiddle 上的运行示例。