MySQL date function

The database used in the following , May refer to Create exercise database

Return current date

1. function ：CURDATE()

2. Instructions

   SELECT CURDATE();
   

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Return current time

1. function ：CURTIME()

2. Instructions

   SELECT CURTIME();
   

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Returns the current date and time

1. function ：NOW()

2. Instructions

   SELECT NOW()
   

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Extract date value

1. function ：DATE()

2. Instructions

   SELECT DATE('2021-10-31 11:36:20')
   

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Extract the year value

1. function ：YEAR()

2. Instructions

   SELECT YEAR('2021-10-31 11:36:20')
   

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Extract the month value

1. function ：MONTH()

2. Instructions

   SELECT MONTH('2021-10-31 11:36:20')
   

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Extract the day value

1. function ：DAY()

2. Instructions

   SELECT DAY('2021-10-31 11:36:20')
   

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Extract the hour value

1. function ：HOUR()

2. Instructions

   SELECT HOUR('2021-10-31 11:36:20')
   

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Extract the minute value

1. function ：MINUTE()

2. Instructions

   SELECT MINUTE('2021-10-31 11:36:20')
   

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Extract second value

1. function ：SECOND()

2. Instructions

   SELECT SECOND('2021-10-31 11:36:20')
   

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Convert seconds into time

1. function ：SEC_TO_TIME

2. Instructions

   SELECT SEC_TO_TIME(3661)
   

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Turn the time into seconds

1. function ：TIME_TO_SEC()

2. Instructions

   SELECT TIME_TO_SEC('1:01:01')
   

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Calculation n Days after

1. function ：ADDDATE(d,n)

2. explain ：d Indicates the date ,n Days .

3. Instructions

   SELECT ADDDATE('2021-10-31',10)
   

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Calculation n The day before

1. function ：SUBDATE(d,n)

2. explain ：d Indicates the date ,n Days .

3. Instructions

   SELECT SUBDATE('2021-10-31 12:23:20',10)
   

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Calculation n Time in seconds

1. function ：ADDTIME(t,n)

2. explain ：t Time ,n Indicates the time interval , When n When it is an integer, it should be less than 60, It can also be expressed as a string .

3. Instructions

   SELECT ADDTIME('2021-10-31 11:43:25',5),ADDTIME('2021-10-31 11:43:25','2:10:15')
   

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Calculation n Seconds ago

1. function ：SUBTIME()

2. explain ：t Time ,n Indicates the time interval , When n When it is an integer, it should be less than 60, It can also be expressed as a string .

3. Instructions

   SELECT SUBTIME('2021-10-31 12:23:20',10),SUBTIME('2021-10-31 12:23:20','2:3:20')
   

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Calculate the date interval

1. function ：DATEDIFF(d1,d2)

2. explain ：d1 End date ,d2 Start date .

3. Instructions

   SELECT DATEDIFF('2022-01-01','2021-10-31'),DATEDIFF('2021-10-31','2022-01-01')
   

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Calculate the time interval

1. function ：TIMEDIFF(t1,t2)

2. explain ：t1 It's the start time t2 End time

3. Instructions

   SELECT TIMEDIFF('12:31:20','11:30:10')
   

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practice ： Calculation xs The ages of all the people in the table

1. Instructions

   select  Student number , full name , Date of birth ,DATEDIFF(NOW(), Date of birth ) DIV 365 as  Age  from xs;
   

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