Create column for a table from select data from another table column

Question

0.00/5 (No votes)

See more:

I have a table that shows the date information of a topic.

`FirstTable` looks like this:

|id|DateP|
|---|---|
|1|1397/01/02|
|2|1398/05/09|
|3|1398/06/07|
|4|1398/08/09|
|5|1399/02/01|

I want to create columns for another table that are the result of selecting the DateP column from FirstTable.

`SecondTable` looks like this:

|id|1397/01/02|1398/05/09|1398/06/07|1398/08/09|1399/02/01|
|---|---|---|---|---|---|
|1||||||
|2||||||
|3||||||

Please guide me in finding the SQL code.

What I have tried:

DECLARE @i INT = 0;
DECLARE @DatTim NVARCHAR(50)='';
SELECT @count=  Count(*) FROM FirstTable

WHILE @i <= @count
BEGIN
    @DatTim=(select DateP+TimeP FROM FirstTable where id=@i)   
    ALTER TABLE SecondTable ADD @DatTim NVARCHAR(50);
    SET @i = @i + 1;
END

Posted 19-Sep-21 18:22pm

shahab kimiayee

Updated 21-Sep-21 11:53am

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

shahab kimiayee · Answer 1 · 2021-09-19T19:33:00

Thanks to the members, thank God, I was able to find a solution:

DECLARE @i INT = 1;
DECLARE @count INT = 0;
DECLARE @DatTim NVARCHAR(50)='';
Set @count=(select Count(*) FROM FirstTable)

WHILE @i <= @count
BEGIN
    Set @DatTim=(select DateP FROM FirstTable where id=@i)   
    exec ('ALTER TABLE SecondTable ADD ['+@DatTim +'] int NULL')
    SET @i = @i + 1;
END

atmtrujillo · Answer 2 · 2021-09-21T11:53:00

This is idempotent and with no loops. Good luck!

SQL

/*
CREATE TABLE dbo.FirstTable (id INT, DateP DATE);

INSERT INTO dbo.FirstTable (id, DateP)
VALUES (1,'1397/01/02')
,(2,'1398/05/09')
,(3,'1398/06/07')
,(4,'1398/08/09')
,(5,'1399/02/01');
*/

IF OBJECT_ID(N'dbo.SecondTable') IS NULL
	CREATE TABLE dbo.SecondTable (id INT NOT NULL IDENTITY PRIMARY KEY);

DECLARE @tsql NVARCHAR(MAX) = N'';

SELECT @tsql = @tsql + N'
IF NOT EXISTS (SELECT 1 FROM sys.columns WHERE object_id = OBJECT_ID(N''dbo.SecondTable'') AND name = N''' + CONVERT(NVARCHAR(10), DateP, 111) + ''')
	ALTER TABLE dbo.SecondTable ADD [' + CONVERT(NVARCHAR(10), DateP, 111) + N'] NVARCHAR(50);'
FROM dbo.FirstTable
ORDER BY id;

PRINT @tsql;
EXEC sys.sp_executesql @tsql;

Create column for a table from select data from another table column

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0