Rebuild all indexes on SQL Server

Exec sp_msforeachtable 'SET QUOTED_IDENTIFIER ON; ALTER INDEX ALL ON ? REBUILD'

Or for a full rebuild across multiple databases.

DECLARE @Database NVARCHAR(255)
DECLARE @Table NVARCHAR(255)
DECLARE @cmd NVARCHAR(1000)

DECLARE DatabaseCursor CURSOR READ_ONLY
FOR
SELECT name
FROM master.sys.databases
WHERE name NOT IN (
		'master'
		,'msdb'
		,'tempdb'
		,'model'
		,'distribution'
		,'rdsadmin'
		) -- databases to exclude
	--WHERE name IN ('DB1', 'DB2') -- use this to select specific databases and comment out line above
	AND STATE = 0 -- database is online
	AND is_in_standby = 0 -- database is not read only for log shipping
ORDER BY 1

OPEN DatabaseCursor

FETCH NEXT
FROM DatabaseCursor
INTO @Database

WHILE @@FETCH_STATUS = 0
BEGIN
	SET @cmd = 'DECLARE TableCursor CURSOR READ_ONLY FOR SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' +  
   table_name + '']'' as tableName FROM [' + @Database + '].INFORMATION_SCHEMA.TABLES WHERE table_type = ''BASE TABLE'''

	-- create table cursor  
	EXEC (@cmd)

	OPEN TableCursor

	FETCH NEXT
	FROM TableCursor
	INTO @Table

	WHILE @@FETCH_STATUS = 0
	BEGIN
		BEGIN TRY
			SET @cmd = 'ALTER INDEX ALL ON ' + @Table + ' REBUILD' -- with (sort_in_tempdb = on, fillfactor = 90)

			RAISERROR (
					@cmd
					,10
					,1
					) -- uncomment if you want to see commands

			EXEC (@cmd)
		END TRY

		BEGIN CATCH
			PRINT '---'
			PRINT ERROR_MESSAGE()
			PRINT '---'
		END CATCH

		FETCH NEXT
		FROM TableCursor
		INTO @Table
	END

	CLOSE TableCursor

	DEALLOCATE TableCursor

	FETCH NEXT
	FROM DatabaseCursor
	INTO @Database
END

CLOSE DatabaseCursor

DEALLOCATE DatabaseCursor