I want to get all table names which has 3 specific columns.
What I want is from information schema I want to get all table names which contains columnA
AND columnB
AND columnC
.
Currently I am using a query like
SELECT DISTINCT TABLE_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME='columnA'
AND TABLE_SCHEMA='mysampledatabase';
How can I extend the above query and select tables which contains column names columnA
and columnB
?
I came across this answer and other similar answers. They have answered following:
SELECT DISTINCT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME IN ('columnA','ColumnB') AND TABLE_SCHEMA='YourDatabase';
However what they select any table which has either of the 3 columns. I believe that is because of WHERE COLUMN_NAME IN ('columnA','ColumnB','ColumnC')
which , i believe, is equivalent to COLUMN_NAME = 'columnA' OR COLUMN_NAME = 'columnB' OR COLUMN_NAME = 'columnC'
I have tried to replace the WHERE clause with WHERE COLUMN_NAME='columnA' AND COLUMN_NAME='columnB' AND COLUMN_NAME='columnC'
which obviously doesn't return any results because COLUMN_NAME
can only be 1 value at a time!
This is a faster version:
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME IN ('columnA','columnB','columnC')
group by TABLE_NAME
having count(distinct COLUMN_NAME) = 3
In above query having count will have no. of columns specified in IN
phrase.
or try following(but it will create disaster for so many columns. So avoid it)
SELECT DISTINCT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME IN
( SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'columnA' )
and TABLE_NAME in
( SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'columnB')
and TABLE_NAME in
( SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'columnC')
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