三个字:强、大、全,强力推荐之 SQL语句 查询结果 select (timestamp 2005-01-17 10:00 - timestamp 2005-01-01); 16 10:10 select (timestamp 2005-01-17 10:00 - timestamp 2005-01-01) / 7; 2 08:17:08.571429 select (timestamp 2005-01-17 10:00 - tim
三个字:强、大、全,强力推荐之
SQL语句 | 查询结果 |
---|---|
select (timestamp '2005-01-17 10:00' - timestamp '2005-01-01'); |
16 10:10 |
select (timestamp '2005-01-17 10:00' - timestamp '2005-01-01') / 7; |
2 08:17:08.571429 |
select (timestamp '2005-01-17 10:00' - timestamp '2005-01-01') day; |
16 |
select cast((timestamp '2005-01-17 10:00' - timestamp '2005-01-01') day as integer) / 7; |
2 |
select floor((timestamp '2005-01-17 10:00' - timestamp '2005-01-01') / interval '7'); |
2 |
select timestamptz '2009-05-29 15:21:00.456789'; |
2009-05-2915:21:00.456789-04 |
select timestamptz '2009-05-28'; |
2009-05-2800:00:00-04 |
select timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28'; |
1 15:21:00.456789 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28'); |
1 15:21:00.456789 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28')(3); |
1 15:21:00.457 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28')second; |
141660.456789 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') year; |
0 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2007-01-01') month; |
28 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2007-01-01') year; |
2 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2007-01-01') year to month; |
2-4 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') second(3); |
141660.457 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') minute(3); |
2361 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') minute; |
2361 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') minute to second(3); |
2361:00.457 |
select (timestamptz '2009-05-29 15:21:00.456789'-timestamptz '2009-05-28') minute to second; |
2361:00.456789 |

MySQLviewshavelimitations:1)Theydon'tsupportallSQLoperations,restrictingdatamanipulationthroughviewswithjoinsorsubqueries.2)Theycanimpactperformance,especiallywithcomplexqueriesorlargedatasets.3)Viewsdon'tstoredata,potentiallyleadingtooutdatedinforma

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ToaddauserinMySQL,use:CREATEUSER'username'@'host'IDENTIFIEDBY'password';Here'showtodoitsecurely:1)Choosethehostcarefullytocontrolaccess.2)SetresourcelimitswithoptionslikeMAX_QUERIES_PER_HOUR.3)Usestrong,uniquepasswords.4)EnforceSSL/TLSconnectionswith

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