The SELECT T.T IME, t. * FROM (SELECT * FROM T_TJJC_M_CARTYPE_HOUR_CZC T1
FULL JOIN T_TJJC_M_CARTYPE_HOUR_SJ T2 ON T1. TIME=T2. The TIME
FULL JOIN T_TJJC_M_CARTYPE_HOUR_GJ T3 ON T2. TIME=T3. The TIME
) T WHERE T.T IME='1899/12/30 1:00:00'

- there is no check to the data, get rid of the join of two tables to check the data after the

CodePudding user response:

SELECT * FROM T_TJJC_M_CARTYPE_HOUR_CZC T1

Write here is *, three tables of TIME were found out, which one do you want to display?

Must write the select T1 TIME,. T1, T2. COL_2 COL_A from T1...

CodePudding user response:

You're right, but I just want to condition selection of three table all the time to get three tables associated, if after the associated still can look up a table of the time, that is not associated to the meaning? That how do I filter of the three tables all time terms?

CodePudding user response:

 - you use here is full join, you use this function in the inner to 

-- you can COALESCE, baidu once his usage 
The select COALESCE (t1 time, t2. Time, t3. Time) time,. T1, t2. Col_b col_a 
The from t1 full join b... 

CodePudding user response:

, there is a record at the back of the filter is useful, if there is, how can you found out

CodePudding user response:

reference wmxcn2000 reply: 3/f

 - you use here is full join, you use this function in the inner to 

-- you can COALESCE, baidu once his usage 
The select COALESCE (t1 time, t2. Time, t3. Time) time,. T1, t2. Col_b col_a 
The from t1 full join b... 

I tried this data can be found, but the query result is not what I want, this function returns only one time of t1 or t2 or t3, rather than three tables I want all the time

CodePudding user response:

reference 5 floor zhanghuizzfftt reply:

this I tried data can be found, but the query result is not what I want, this function returns only one time of t1 or t2 or t3, rather than the three tables I need all the time

 - for the three time alias 

The select t1, time time1, t2 time tim2, t3. Time time3 the from... 

CodePudding user response:

First to understand the FULL meaning of the JOIN