SQL gets the intersection of the selected time

Such as: T1,t2 represents the time period to select, T3,T4 represents the system time.

So if you want to get all the intersections for the selected time period:

Conditions 1 and ((T3>T1 and T1>t2) or (T3<T2 and T2<T4) or (T3<T2 and T1<T4)) .... Condition 3 ...

PS: Condition 1, Condition 3 stands for other conditions, the intersection of the selected time means that the selected time period is the same as the time interval of the system field itself.

SQL gets the intersection of the selected time