-- Drop any existing TeamId column from 000094_threads_teamid.up.sql
SET @preparedStatement = (SELECT IF(
    EXISTS(
        SELECT 1 FROM INFORMATION_SCHEMA.STATISTICS
        WHERE table_name = 'Threads'
        AND table_schema = DATABASE()
        AND column_name = 'TeamId'
    ) > 0,
    'ALTER TABLE Threads DROP COLUMN TeamId;',
    'SELECT 1;'
));

PREPARE removeColumnIfExists FROM @preparedStatement;
EXECUTE removeColumnIfExists;
DEALLOCATE PREPARE removeColumnIfExists;

SET @preparedStatement = (SELECT IF(
    NOT EXISTS(
        SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
        WHERE table_name = 'Threads'
        AND table_schema = DATABASE()
        AND column_name = 'ThreadTeamId'
    ),
    'ALTER TABLE Threads ADD COLUMN ThreadTeamId varchar(26) DEFAULT NULL;',
    'SELECT 1;'
));

PREPARE addColumnIfNotExists FROM @preparedStatement;
EXECUTE addColumnIfNotExists;
DEALLOCATE PREPARE addColumnIfNotExists;

UPDATE Threads, Channels
SET Threads.ThreadTeamId = Channels.TeamId
WHERE Channels.Id = Threads.ChannelId
AND Threads.ThreadTeamId IS NULL;