T-SQL - Copying & Transposing Data - sql

Question

I'm trying to copy data from one table to another, while transposing it and combining it into appropriate rows, with different columns in the second table.
First time posting. Yes this may seem simple to everyone here. I have tried for a couple hours to solve this. I do not have much support internally and have learned a great deal on this forum and managed to get so much accomplished with your other help examples. I appreciate any help with this.
Table 1 has the data in this format.
Type Date Value
--------------------
First 2019 1
First 2020 2
Second 2019 3
Second 2020 4
Table 2 already has the Date rows populated and columns created. It is waiting for the Values from Table 1 to be placed in the appropriate column/row.
Date First Second
------------------
2019 1 3
2020 2 4

Answer 1

For an update, I might use two joins:
update t2
set first = tf.value,
second = ts.value
from table2 t2 left join
table1 tf
on t2.date = tf.date and tf.type = 'First' left join
table1 ts
on t2.date = ts.date and ts.type = 'Second'
where tf.date is not null or ts.date is not null;

Answer 2

use conditional aggregation
select date,max(case when type='First' then value end) as First,
max(case when type='Second' then value end) as Second from t
group by date

Answer 3

You can do conditional aggregation :
select date,
max(case when type = 'first' then value end) as first,
max(case when type = 'Second' then value end) as Second
from table t
group by date;
After that you can use cte :
with cte as (
select date,
max(case when type = 'first' then value end) as first,
max(case when type = 'Second' then value end) as Second
from table t
group by date
)
update t2
set t2.First = t1.First,
t2.Second = t1.Second
from table2 t2 inner join
cte t1
on t1.date = t2.date;

Answer 4

Seems like you're after a PIVOT
DECLARE #Table1 TABLE
(
[Type] NVARCHAR(100)
, [Date] INT
, [Value] INT
);
DECLARE #Table2 TABLE(
[Date] int
,[First] int
,[Second] int
)
INSERT INTO #Table1 (
[Type]
, [Date]
, [Value]
)
VALUES ( 'First', 2019, 1 )
, ( 'First', 2020, 2 )
, ( 'Second', 2019, 3 )
, ( 'Second', 2020, 4 );
INSERT INTO #Table2 (
[Date]
)
VALUES (2019),(2020)
--Show us what's in the tables
SELECT * FROM #Table1
SELECT * FROM #Table2
--How to pivot the data from Table 1
SELECT * FROM #Table1
PIVOT (
MAX([Value]) --Pivot on this Column
FOR [Type] IN ( [First], [Second] ) --Make column where [Value] is in one of this
) AS [pvt] --Table alias
--which gives
--Date First Second
------------- ----------- -----------
--2019 1 3
--2020 2 4
--Using that we can update #Table2
UPDATE [tbl2]
SET [tbl2].[First] = pvt.[First]
,[tbl2].[Second] = pvt.[Second]
FROM #Table1 tbl1
PIVOT (
MAX([Value]) --Pivot on this Column
FOR [Type] IN ( [First], [Second] ) --Make column where [Value] is in one of this
) AS [pvt] --Table alias
INNER JOIN #Table2 tbl2 ON [tbl2].[Date] = [pvt].[Date]
--Results from #Table 2 after updated
SELECT * FROM #Table2
--which gives
--Date First Second
------------- ----------- -----------
--2019 1 3
--2020 2 4