Check the Query Store is enabled or disabled for the databases in SQL Server

Query Store helps in identifying performance caused by query plan changes.
It captures a history of queries, plans, and runtime statistics, and retains these for your review.

Check whether the Query Store is enabled or disabled for the database:

select name,database_id,is_query_store_on from sys.databases

--Check the query store different options:
select * from  sys.database_query_store_options

Enable the Query Store in SQL Server:

USE [master]
GO
ALTER DATABASE [AdventureWorks2017] SET QUERY_STORE = ON
GO
ALTER DATABASE [AdventureWorks2017] SET QUERY_STORE (OPERATION_MODE = READ_WRITE)
GO


OR 

ALTER DATABASE [database_name]
SET QUERY_STORE = ON
    (
      OPERATION_MODE = READ_WRITE,
      CLEANUP_POLICY = ( STALE_QUERY_THRESHOLD_DAYS = 90 ),
      DATA_FLUSH_INTERVAL_SECONDS = 900,
      QUERY_CAPTURE_MODE = AUTO,
      MAX_STORAGE_SIZE_MB = 1024,
      INTERVAL_LENGTH_MINUTES = 60
    );

Disable the Query Store in SQL Server

USE [master]
GO
ALTER DATABASE [AdventureWorks2017] SET QUERY_STORE = OFF

OR 
-- Force fully disable:
ALTER DATABASE [DBName] SET QUERY_STORE = OFF (FORCED)

Manually clear the query store cache data:

ALTER DATABASE [DBName] SET QUERY_STORE CLEAR; 

Check query from query store:

SELECT Txt.query_text_id, Txt.query_sql_text, Pl.plan_id, Qry.*
FROM sys.query_store_plan AS Pl
INNER JOIN sys.query_store_query AS Qry
    ON Pl.query_id = Qry.query_id
INNER JOIN sys.query_store_query_text AS Txt
    ON Qry.query_text_id = Txt.query_text_id;

Script for enabling or disabling all the databases for Query Store:

-- Enable all the databases in the server:

-- Read write mode
SELECT 'ALTER DATABASE ['+name+'] SET QUERY_STORE = ON (OPERATION_MODE = READ_WRITE);'
FROM sys.databases
WHERE name NOT IN ('master', 'model', 'tempdb', 'msdb', 'Resource')
AND is_query_store_on = 0;

--Read only mode:
SELECT 'ALTER DATABASE ['+name+'] SET QUERY_STORE = ON (OPERATION_MODE = READ_ONLY);'
FROM sys.databases
WHERE name NOT IN ('master', 'model', 'tempdb', 'msdb', 'Resource')
AND is_query_store_on = 0;

--Disable all the databases:
SELECT 'ALTER DATABASE ['+name+'] SET QUERY_STORE = OFF;'
FROM sys.databases
WHERE name NOT IN ('master', 'model', 'tempdb', 'msdb', 'Resource')
AND is_query_store_on = 1;