mysql 如何合并两个库

-- 重命名表
RENAME TABLE db1.table1 TO db1.new_table1;
RENAME TABLE db2.table1 TO db2.new_table1;

-- 使用事务保证数据一致性
START TRANSACTION;
INSERT INTO new_db.new_table (column1, column2)
SELECT column1, column2 FROM db1.old_table
UNION ALL
SELECT column1, column2 FROM db2.old_table;
COMMIT;

-- 分批迁移数据
SET @batch_size = 1000;
SET @offset = 0;

WHILE (SELECT COUNT(*) FROM db1.old_table LIMIT @offset, 1) > 0 DO
    INSERT INTO new_db.new_table (column1, column2)
    SELECT column1, column2 FROM db1.old_table LIMIT @offset, @batch_size;
    SET @offset = @offset + @batch_size;
END WHILE;