Select column names from one table based off of values in column of another table

Question

This could be a repost; if so, link me and I will delete.

First off, I am a SQL newb. I have two tables, table_1 and table_2. I want to select the column names from table_1 that only correspond to values found in a column named 'foo' from table 2.

How can I got about this? Does this require an inner join?

I have some code I can post, but it is a disaster.

http://stackoverflow.com/questions/5637983/sql-select-dynamic-column-name-based-on-variable — Brino, Jun 18 '15 at 03:33
I am not sure that post answers my question. Could you elaborate on why this post could help? — branch.lizard, Jun 18 '15 at 03:47
I updated my answer please check it. After you satisfied my answer can you give tick mark and up vote please. — Venkatesh Panabaka, Jun 18 '15 at 04:05

Venkatesh Panabaka · Accepted Answer · 2015-06-18T04:04:41.247

1

These is one type of example.

select * from table1 join table2 on table1.col1= table2.col2

we follow these above syntax.

select * from table1 join table2 on table1.col1= table2.foo

These is the how find out column_name is present in another table

SELECT * FROM(    SELECT letter  FROM `Table_2` ) a JOIN
(SELECT `COLUMN_NAME` 
FROM `INFORMATION_SCHEMA`.`COLUMNS` 
WHERE `TABLE_SCHEMA`='database_name' 
    AND `TABLE_NAME`='Table_1') b ON a.letter= b. COLUMN_NAME

Thank you.

edited Jun 18 '15 at 04:04

answered Jun 18 '15 at 03:35

Venkatesh Panabaka

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This is joining the two tables based on common values found in columns. I am wanting to join based on column names of table_1 and values found in column foo in table_2. Am I way off track here? Thank you for your quick reply. – branch.lizard Jun 18 '15 at 03:39
I am referencing the column names in table_1 by select "column_name" FROM "information_schema"."columns" WHERE "table_name" = 'table_1' – branch.lizard Jun 18 '15 at 03:42
you don't know what columns in table_1 to compare in table_2 correct? – Venkatesh Panabaka Jun 18 '15 at 03:43
No, I do not want to select any columns from table_1. I want to select the names of the columns in table_1 (not their values). – branch.lizard Jun 18 '15 at 03:45
You want only empty columns in table1 ? – Venkatesh Panabaka Jun 18 '15 at 03:46
No, not empty columns. The information I want to select is all of the column identifiers from table_1 which are found in the foo column of table_2. – branch.lizard Jun 18 '15 at 03:48
Table_1 has columns "A" "B" "C" "D". Table_2 has column "letter: Column "letter" has values 'A' 'B' 'C'. The columns 'A' 'B' 'C' match up to the values in column 'letter'. How can I design a query which does this? – branch.lizard Jun 18 '15 at 03:54
Ok, i understood now give me few minutes. I will update my answer. Thanks for providing valuable information. – Venkatesh Panabaka Jun 18 '15 at 03:56
Excellent. That worked. Thank you for your help. Upvoted. – branch.lizard Jun 18 '15 at 04:10

Select column names from one table based off of values in column of another table

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