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前言:
遇到朋友提問(wèn),如下:
SELECT * FROM ali_users WHERE DATEDIFF(CAST(CONCAT(DATE_FORMAT(NOW(),'%y'),DATE_FORMAT(birthday,'-%m-%d'))AS DATE),CAST(DATE_FORMAT(NOW(),'%y-%m-%d') AS DATE)) <=1
1,準(zhǔn)備測(cè)試數(shù)據(jù),需要包含跨年的數(shù)據(jù)
1.1,準(zhǔn)備測(cè)試數(shù)據(jù)的SQL
USE test;
DROP TABLE IF EXISTS ali_users;
CREATE TABLE ali_users (username VARCHAR(10),birthday DATE NOT NULL,iphone VARCHAR(16));
INSERT INTO ali_users SELECT \'MaoYi\',\'1985-09-04\',\'13998786543\' UNION ALL
SELECT \'LiuEr\',\'1985-08-30\',\'13998786543\' UNION ALL
SELECT \'ZhangSan\',\'1981-01-01\',\'13998786543\' UNION ALL
SELECT \'LiSi\',\'1983-01-02\',\'13998786543\' UNION ALL
SELECT \'WangWu\',\'1984-11-01\',\'13998786543\' UNION ALL
SELECT \'ZhaoLiu\',\'1984-11-01\',\'13998786543\' UNION ALL
SELECT \'SongQi\',\'1986-08-31\',\'13998786543\' UNION ALL
SELECT \'HuangBa\',\'1989-09-01\',\'13998786543\' UNION ALL
SELECT \'ZengJiu\',\'1989-09-02\',\'13998786543\' UNION ALL
SELECT \'LuoShi\',\'1985-09-03\',\'13998786543\' UNION ALL
SELECT \'Tom\',\'1995-09-05\',\'13998786543\' UNION ALL
SELECT \'Licy\',\'1991-12-30\',\'13998286543\' UNION ALL
SELECT \'Cari\',\'1992-12-31\',\'13998286543\' UNION ALL
SELECT \'Mark\',\'1992-01-03\',\'13998286543\' UNION ALL
SELECT \'Ruby\',\'1992-01-04\',\'13998286547\';
1.2,在數(shù)據(jù)庫(kù)命令行執(zhí)行SQL
mysql> USE test;
DATABASE CHANGED
mysql> DROP TABLE IF EXISTS ali_users;
QUERY OK, 0 ROWS affected (0.00 sec)
mysql> CREATE TABLE ali_users (username VARCHAR(10),birthday DATE NOT NULL,iphone VARCHAR(16));
QUERY OK, 0 ROWS affected (0.01 sec)
mysql> INSERT INTO ali_users SELECT \'MaoYi\',\'1985-09-04\',\'13998786543\' UNION ALL
-> SELECT \'LiuEr\',\'1985-08-30\',\'13998786543\' UNION ALL
-> SELECT \'ZhangSan\',\'1981-01-01\',\'13998786543\' UNION ALL
-> SELECT \'LiSi\',\'1983-01-02\',\'13998786543\' UNION ALL
-> SELECT \'WangWu\',\'1984-11-01\',\'13998786543\' UNION ALL
-> SELECT \'ZhaoLiu\',\'1984-11-01\',\'13998786543\' UNION ALL
-> SELECT \'SongQi\',\'1986-08-31\',\'13998786543\' UNION ALL
-> SELECT \'HuangBa\',\'1989-09-01\',\'13998786543\' UNION ALL
-> SELECT \'ZengJiu\',\'1989-09-02\',\'13998786543\' UNION ALL
-> SELECT \'LuoShi\',\'1985-09-03\',\'13998786543\' UNION ALL
-> SELECT \'Tom\',\'1995-09-05\',\'13998786543\' UNION ALL
-> SELECT \'Licy\',\'1991-12-30\',\'13998286543\' UNION ALL
-> SELECT \'Cari\',\'1992-12-31\',\'13998286543\' UNION ALL
-> SELECT \'Mark\',\'1992-01-03\',\'13998286543\' UNION ALL
-> SELECT \'Ruby\',\'1992-01-04\',\'13998286547\';
QUERY OK, 15 ROWS affected (0.01 sec)
Records: 15 Duplicates: 0 WARNINGS: 0
mysql> SELECT * FROM ali_users;
+----------+------------+-------------+
| username | birthday | iphone |
+----------+------------+-------------+
| MaoYi | 1985-09-04 | 13998786543 |
| LiuEr | 1985-08-30 | 13998786543 |
| ZhangSan | 1981-01-01 | 13998786543 |
| LiSi | 1983-01-02 | 13998786543 |
| WangWu | 1984-11-01 | 13998786543 |
| ZhaoLiu | 1984-11-01 | 13998786543 |
| SongQi | 1986-08-31 | 13998786543 |
| HuangBa | 1989-09-01 | 13998786543 |
| ZengJiu | 1989-09-02 | 13998786543 |
| LuoShi | 1985-09-03 | 13998786543 |
| Tom | 1995-09-05 | 13998786543 |
| Licy | 1991-12-30 | 13998286543 |
| Cari | 1992-12-31 | 13998286543 |
| Mark | 1992-01-03 | 13998286543 |
| Ruby | 1992-01-04 | 13998286547 |
+----------+------------+-------------+
15 ROWS IN SET (0.00 sec)
mysql>
2,寫出查詢SQL
SELECT * FROM ali_users WHERE
2,1,跨年問(wèn)題分析
因?yàn)榭缒甑臅r(shí)候生日字段通常月份比較小是1月,所以如果利用DATEDIFF來(lái)判斷要與月份比較大12月來(lái)比較得到相差天數(shù)在N天之內(nèi)的話,就需要YEAR(NOW())+1,當(dāng)年年份+1再加上月份才能與NOW()比較得出真實(shí)的相差天數(shù)。
2.2,5天之內(nèi)的設(shè)定
N天之內(nèi),用 BETWEEN 0 AND N 來(lái)判斷,如果是5天之內(nèi)(包含今天)那么N值就是4,就是 BETWEEN 0 AND 4
3,驗(yàn)證數(shù)據(jù)
比如提醒最近5天之內(nèi)(包括今日)過(guò)生日的同事,生日快樂(lè)。
3.1,查詢的數(shù)據(jù)都在今年之內(nèi)的,比如今天是8月30日,那么需要執(zhí)行的SQL如下:
SELECT * FROM ali_users WHERE
查詢的結(jié)果應(yīng)該是從今天8月30日到9月3日之間過(guò)生日的同事,包括LiuEr,SongQi,HuangBa,ZengJiu,LuoShi;
mysql> SELECT * FROM ali_users WHERE
-> DATEDIFF(CAST(CONCAT(YEAR(NOW()),DATE_FORMAT(birthday,\'-%m-%d\'))AS DATE),CAST(DATE_FORMAT(NOW(),\'%y-%m-%d\') AS DATE)) BETWEEN 0 AND 4
-> OR/* or后面的是捎帶解決跨年問(wèn)題*/
-> DATEDIFF(CAST(CONCAT(YEAR(NOW())+1,DATE_FORMAT(birthday,\'-%m-%d\'))AS DATE),CAST(DATE_FORMAT(NOW(),\'%y-%m-%d\') AS DATE)) BETWEEN 0 AND 4
-> ;
+----------+------------+-------------+
| username | birthday | iphone |
+----------+------------+-------------+
| LiuEr | 1985-08-30 | 13998786543 |
| SongQi | 1986-08-31 | 13998786543 |
| HuangBa | 1989-09-01 | 13998786543 |
| ZengJiu | 1989-09-02 | 13998786543 |
| LuoShi | 1985-09-03 | 13998786543 |
+----------+------------+-------------+
5 ROWS IN SET (0.00 sec)
mysql>
3.2,查詢的生日有跨年的
比如今天是2013年12月30日,要查詢5天之內(nèi)過(guò)生日的同事,那么就有2013年的12月30日31日過(guò)生日的,也有2014年1月1日2日3日過(guò)生日的同事,因?yàn)榻裉焓?月30日,所以要把Step#2中的SQL的NOW()改成'2013-12-30 00:10:10'來(lái)進(jìn)行測(cè)試,SQL整理如下:
mysql> SELECT * FROM ali_users WHERE
-> DATEDIFF(CAST(CONCAT(YEAR(\'2013-12-30 00:10:10\'),DATE_FORMAT(birthday,\'-%m-%d\'))AS DATE),CAST(DATE_FORMAT(\'2013-12-30 00:10:10\',\'%y-%m-%d\') AS DATE)) BETWEEN 0 AND 4
-> OR/* or后面的是捎帶解決跨年問(wèn)題*/
-> DATEDIFF(CAST(CONCAT(YEAR(\'2013-12-30 00:10:10\')+1,DATE_FORMAT(birthday,\'-%m-%d\'))AS DATE),CAST(DATE_FORMAT(\'2013-12-30 00:10:10\',\'%y-%m-%d\') AS DATE)) BETWEEN 0 AND 4
-> ;
+----------+------------+-------------+
| username | birthday | iphone |
+----------+------------+-------------+
| ZhangSan | 1981-01-01 | 13998786543 |
| LiSi | 1983-01-02 | 13998786543 |
| Licy | 1991-12-30 | 13998286543 |
| Cari | 1992-12-31 | 13998286543 |
| Mark | 1992-01-03 | 13998286543 |
+----------+------------+-------------+
5 ROWS IN SET (0.00 sec)
mysql>
4,總結(jié)
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