MySQL按日期分組並統計截止當前時間的總數（實例教程）

MySQL按日期分組並統計截止當前時間的總數

建表語句

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for t_reg
-- ----------------------------
DROP TABLE IF EXISTS `t_reg`;
CREATE TABLE `t_reg`  (
  `ID` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID編號',
  `REG_TIME` datetime(0) NULL DEFAULT NULL COMMENT '時間',
  `REG_COUNT` int(11) NULL DEFAULT NULL COMMENT '數量',
  PRIMARY KEY (`ID`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 8 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_reg
-- ----------------------------
INSERT INTO `t_reg` VALUES (1, '2019-05-01 08:08:12', 1);
INSERT INTO `t_reg` VALUES (2, '2019-05-02 00:09:09', 10);
INSERT INTO `t_reg` VALUES (3, '2019-05-02 13:08:08', 2);
INSERT INTO `t_reg` VALUES (4, '2019-05-03 15:08:05', 4);
INSERT INTO `t_reg` VALUES (5, '2019-05-03 17:08:08', 6);
INSERT INTO `t_reg` VALUES (6, '2019-05-16 21:01:12', 4);
INSERT INTO `t_reg` VALUES (7, '2019-05-03 05:08:09', 11);

SET FOREIGN_KEY_CHECKS = 1;

表結構以下所示：REG_COUNT  表示當天新增的用戶數

如今的需求是這樣的：按天天分組，查詢當天新增的用戶總數和截止到當前時間新增的用戶總數，結果以下:

SQL語句以下:

SELECT
    reg_time,
    min_total AS '小計',
    @total := @total + min_total AS '總計' 
FROM
    ( SELECT date( reg_time ) AS reg_time, 
    sum( reg_count ) AS min_total FROM t_reg GROUP BY date( reg_time ) ) AS temp,
    ( SELECT @total := 0 ) AS T1 
ORDER BY
    reg_time;

解釋一下:SELECT @total := 0,,這句的意思是給臨時變量@total設置值爲0;

如此便可得出上面的結果知足需求.