MYSQL (15)

Mysql 日期转换星期

{codecitation class="brush:sql" width="500px"} mysql> SELECT something FROM table WHERE TO_DAYS(NOW()) - TO_DAYS(date_col) <= 30; DAYOFWEEK(date) 返回日期date的星期索引(1=星期天,2=星期一, ……7=星期六)。这些索引值对应于ODBC标准。 mysql> select DAYOFWEEK('1998-02-03'); -> 3 WEEKDAY(date) 返回date的星期索引(0=星期一,1=星期二, ……6= 星期天)。 mysql> select WEEKDAY('1997-10-04 22:23:00'); -> 5 mysql> select WEEKDAY('1997-11-05'); -> 2 DAYOFMONTH(date) 返回date的月份中日期,在1到31范围内。 mysql> select DAYOFMONTH('1998-02-03'); -> 3 DAYOFYEAR(date) 返回date在一年中的日数, 在1到366范围内。 mysql> select DAYOFYEAR('1998-02-03'); -> 34 MONTH(date) 返回date的月份,范围1到12。 mysql> select MONTH('1998-02-03'); -> 2 DAYNAME(date) 返回date的星期名字。 mysql> select DAYNAME("1998-02-05"); -> 'Thursday' MONTHNAME(date) 返回date的月份名字。 mysql> select MONTHNAME("1998-02-05"); -> 'February' QUARTER(date) 返回date一年中的季度,范围1到4。 mysql> select QUARTER('98-04-01'); -> 2 WEEK(date) WEEK(date,first) 对于星期天是一周的第一天的地方,有一个单个参数,返回date的周数,范围在0到52。2个参数形式WEEK()允许你指定星期是否开始于星期天或星期一。如果第二个参数是0,星期从星期天开始,如果第二个参数是1,从星期一开始。 mysql> select WEEK('1998-02-20'); -> 7 mysql> select WEEK('1998-02-20',0); -> 7 mysql> select WEEK('1998-02-20',1); -> 8 YEAR(date) 返回date的年份,范围在1000到9999。…
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CONCAT mysql

使用方法: CONCAT(str1,str2,…) 返回结果为连接参数产生的字符串。如有任何一个参数为NULL ,则返回值为 NULL。
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left join

{codecitation class="brush:sql" width="500px"} SELECT `tbl_cours_info`.crs_nom as cours, concat(`tbl_professeur`.`prof_nom`," ",`tbl_professeur`.`prof_prenom`)as prof, `tbl_emploi_du_temps`.`empl_jours` as jours, `tbl_emploi_du_temps`.`empl_heures_begin` as tbegin, `tbl_emploi_du_temps`.`empl_heures_end` as tendFROM `tbl_emploi_du_temps`LEFT JOIN `tbl_cours_info` ON `tbl_emploi_du_temps`.`empl_cours_id` = `tbl_cours_info`.`crs_id`LEFT JOIN `tbl_professeur` ON `tbl_emploi_du_temps`.`empl_prof_id`= `tbl_professeur`.`prof_id`ORDER BY `tbl_emploi_du_temps`.`empl_jours` ASC {/codecitation}
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mysql add foreign key 外键

{codecitation class="brush:sql" width="500px"} -- -------------------------------------------------------------------------------------------ALTER TALBE tbl_choix_examenADD PRIMARY KEY (choix_examen_id);-- -------------------------------------------------------------------------------------------ALTER TABLE `tbl_choix_examen` ADD PRIMARY KEY ( `choix_examen_id` ) -- -------------------------------------------------------------------------------------------ALTER TABLE `ilci`.`tbl_choix_examen` ADD PRIMARY KEY ( `choix_examen_id` ) ALTER TABLE `tbl_choix_examen` CHANGE `choix_examen_id` `choix_examen_id` INT( 10 ) NOT NULL AUTO_INCREMENT -- -------------------------------------------------------------------------------------------ALTER `ilci`.`tbl_choix_examen` ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name, ...) REFERENCES tbl_name (index_col_name,...) [ON DELETE reference_option] [ON UPDATE reference_option]-- -------------------------------------------------------------------------------------------alter table `ilci`.`tbl_choix_examen` add foreign key(choix_examen_stu_id) references tbl_student(stu_id);-- -------------------------------------------------------------------------------------------alter table `ilci`.`tbl_choix_examen` add foreign key(choix_examen_emploi_id) references tbl_emploi_du_temps(empl_id);-- -------------------------------------------------------------------------------------------alter table `ilci`.`tbl_choix_examen_temps` add foreign key(emploi_du_temps_id) references tbl_emploi_du_temps(empl_id);-- ------------------------------------------------------------------------------------------- {/codecitation}
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