You can read the question in the title. Let's say Table A have a datetime field with "2015-12-01 00:00:00" and Table B "2014-12-01 00:00:00".
你可以读标题中的问题。假设表A有一个datetime字段，“2015-12-01 00:00”，表B“2014-12-01 00:00”。
I want the data row from that table which has the bigger datetime.
我想要那个具有更大datetime的表中的数据行。
Something like "datetime(A.datetime) > datetime(B.datetime)" isn't working.
类似于“datetime(.datetime) > datetime(B.datetime)”的方法不起作用。
Help me.
帮助我。
3 个解决方案
#1
3
When comparing two datetimes they will be interpreted as timestamps, so just doing A.datetime > B.datetime should work just fine.
当比较两个日期时间时，它们将被解释为时间戳，所以只做一个。datetime > B。datetime应该没问题。
#2
1
You should be able to compare the datetime fields as is, A.datetime > B.datetime.
您应该能够比较datetime字段A。datetime > B.datetime。
#3
0
You cannot always do a direct comparison using <, >, <=, >= as the answer suggests. See the MySQL docs https://dev.mysql.com/doc/refman/5.7/en/using-date.html:
您不能总是使用<、>、<=、>=进行直接比较。参见MySQL docs https://dev.mysql.com/doc/refman/5.7/en/using-date.html:
When you compare a DATE, TIME, DATETIME, or TIMESTAMP to a constant string with the <, <=, =, >=, >, or BETWEEN operators, MySQL normally converts the string to an internal long integer for faster comparison (and also for a bit more “relaxed” string checking). However, this conversion is subject to the following exceptions:
当您将日期、时间、DATETIME或时间戳与<、<=、>=、>或操作符之间的常量字符串进行比较时，MySQL通常会将字符串转换为内部的长整数，以便进行更快速的比较(同时还可以进行更“轻松”的字符串检查)。但是，这种转变有下列例外:
- When you compare two columns
- 当你比较两列时
#1
3
When comparing two datetimes they will be interpreted as timestamps, so just doing A.datetime > B.datetime should work just fine.
当比较两个日期时间时，它们将被解释为时间戳，所以只做一个。datetime > B。datetime应该没问题。
#2
1
You should be able to compare the datetime fields as is, A.datetime > B.datetime.
您应该能够比较datetime字段A。datetime > B.datetime。
#3
0
You cannot always do a direct comparison using <, >, <=, >= as the answer suggests. See the MySQL docs https://dev.mysql.com/doc/refman/5.7/en/using-date.html:
您不能总是使用<、>、<=、>=进行直接比较。参见MySQL docs https://dev.mysql.com/doc/refman/5.7/en/using-date.html:
When you compare a DATE, TIME, DATETIME, or TIMESTAMP to a constant string with the <, <=, =, >=, >, or BETWEEN operators, MySQL normally converts the string to an internal long integer for faster comparison (and also for a bit more “relaxed” string checking). However, this conversion is subject to the following exceptions:
当您将日期、时间、DATETIME或时间戳与<、<=、>=、>或操作符之间的常量字符串进行比较时，MySQL通常会将字符串转换为内部的长整数，以便进行更快速的比较(同时还可以进行更“轻松”的字符串检查)。但是，这种转变有下列例外:
- When you compare two columns
- 当你比较两列时