Sqlite insert both even and odd rows in one expression - sql

Question

I am using sqlite3 and I have a sqlite table which has somewhat duplicated/overlapping columns. To illustrate:
No Col1 Col2 Col3 Col4
row1 1 1 1 2 2
row2 2 1 1 3 3
row3 3 2 2 4 4
row4 4 2 2 5 5
Col1 and Col2 stores the same information, however, Col3 and Col4 has different information.
I want to condense the rows into one row like this:
No Col1 Col2 Col3 Col4 Col3.2 Col4.2
row1 1 1 1 2 2 3 3
row3 3 2 2 4 4 5 5
I have created a new table with the columns, and was able to select the odd rows.
INSERT INTO [Table] ( No, Col1, Col2, Col3, Col4
)
SELECT No, Col1, Col2, Col3, Col4
FROM [Table]
WHERE ([No] % 2) = 1
ORDER BY [No];
The result table would be something like:
No Col1 Col2 Col3 Col4 Col3.2 Col4.2
row1 1 1 1 2 2 null null
row3 3 2 2 4 4 null null
Now I am not sure how to insert the even values into the new table. Using similar expressions only insert more rows. Is it possible to do this INSERT INTO expression in one sentence? Or how do I update the new table?

Answer 1

Just join the table with itself based on the following condition. It'll even work if the No column has gaps:
SELECT o.No, o.Col1, o.Col2, o.Col3, o.Col4, e.Col3, e.Col4
FROM t AS o
INNER JOIN t AS e ON o.Col1 = e.Col1
AND o.Col2 = e.Col2
AND o.No < e.No

Answer 2

Use pivoting logic with aggregation:
SELECT
MIN(No) AS No,
MAX(CASE WHEN No % 2 = 1 THEN Col1 END) AS Col1,
MAX(CASE WHEN No % 2 = 1 THEN Col2 END) AS Col2,
MAX(CASE WHEN No % 2 = 1 THEN Col3 END) AS Col3,
MAX(CASE WHEN No % 2 = 1 THEN Col4 END) AS Col4,
MAX(CASE WHEN No % 2 = 0 THEN Col1 END) AS Col1_2,
MAX(CASE WHEN No % 2 = 0 THEN Col2 END) AS Col2_2,
MAX(CASE WHEN No % 2 = 0 THEN Col3 END) AS Col3_2,
MAX(CASE WHEN No % 2 = 0 THEN Col4 END) AS Col4_2
FROM yourTable
GROUP BY
(No-1) / 2;
Demo

Answer 3

Another approach, using window functions added in sqlite 3.25:
CREATE TABLE table2(no INTEGER PRIMARY KEY, col1, col2, col3, col4, "col3.2", "col4.2");
INSERT INTO table2
SELECT *
FROM (SELECT no, col1, col2, col3, col4, lead(col3) OVER win, lead(col4) OVER win
FROM table1
WINDOW win AS (ORDER BY no))
WHERE no % 2 = 1;
which gives
SELECT * FROM table2;
no col1 col2 col3 col4 col3.2 col4.2
---------- ---------- ---------- ---------- ---------- ---------- ----------
1 1 1 2 2 3 3
3 2 2 4 4 5 5