mysqldiff该工具是官方mysql-utilities工具集的一个脚本，可以用来对比不同数据库之间的表结构，或者同个数据库间的表结构
如果在windows下，直接下载mysql-utilities安装就可以了，然后运行后，会跑到命令行下：
1） 基本用法
mysqldiff –server1=admin:123456@192.168.79.10 –server2=admin:123456@192.168.79.11
–difftype=differ test:test
这样就比较两个不同库中的数据库test，假设两个库中库名都是test
也可以比较不同的表
mysqldiff –server1=user@host1 –server2=user@host2 testdb.table1:anotherdb.anothertable
就是使用库名.表名的方式就可以了
下面是出来的一个效果
# mysqldiff –force –server1=root:msandbox@127.0.0.1:21489 –server2=root:msandbox@127.0.0.1:21490 employees:employees
# WARNING: Using a password on the command line interface can be insecure.
# server1 on 127.0.0.1: … connected.
# server2 on 127.0.0.1: … connected.
# Comparing `employees` to `employees` [PASS]
# Comparing `employees`.`departments` to `employees`.`departments` [FAIL]
# Object definitions differ. (–changes-for=server1)
#
— `employees`.`departments`
+++ `employees`.`departments`
@@ -1,6 +1,6 @@
CREATE TABLE `departments` (
`dept_no` char(4) NOT NULL,
– `dept_name` varchar(40) NOT NULL,
+ `dept_name` varchar(256) DEFAULT NULL,
PRIMARY KEY (`dept_no`),
UNIQUE KEY `dept_name` (`dept_name`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
可以看到，默认-号代表左边要比较的server1的变化，+号代表右边server2的不同，
如果要交换，可以使用参数：
–changes-for=server2
如果要在比较不同的时候，强行继续比较下去，要增加–force选项
2） 可以生成差异化的SQL，因为方法1）中，只产生了不同的地方，但如为了生产考虑，
要生成达到server2的脚本，则可以使用参数
–difftype=sql，
则：
mysqldiff –server1=admin:123456@192.168.79.10 –server2=admin:123456@192.168.79.11
–difftype=sql test:test
mysqldiff的核心是使用INFORMATION_SCHEMA
Java代码
-
SHOW CREATE TABLE `departments`;
-
SELECT TABLE_SCHEMA, TABLE_NAME, ENGINE, AUTO_INCREMENT, AVG_ROW_LENGTH, CHECKSUM, TABLE_COLLATION, TABLE_COMMENT, ROW_FORMAT, CREATE_OPTIONS
-
FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;
-
SELECT ORDINAL_POSITION, COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE,
-
COLUMN_DEFAULT, EXTRA, COLUMN_COMMENT, COLUMN_KEY
-
FROM INFORMATION_SCHEMA.COLUMNS
-
WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;
-
SELECT PARTITION_NAME, SUBPARTITION_NAME, PARTITION_ORDINAL_POSITION,
-
SUBPARTITION_ORDINAL_POSITION, PARTITION_METHOD, SUBPARTITION_METHOD,
-
PARTITION_EXPRESSION, SUBPARTITION_EXPRESSION, PARTITION_DESCRIPTION
-
FROM INFORMATION_SCHEMA.PARTITIONS
-
WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;
-
SELECT CONSTRAINT_NAME, COLUMN_NAME, REFERENCED_TABLE_SCHEMA,
-
REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME
-
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
-
WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
AND
-
REFERENCED_TABLE_SCHEMA IS NOT NULL;
-
SELECT TABLE_SCHEMA, TABLE_NAME, ENGINE, AUTO_INCREMENT, AVG_ROW_LENGTH, CHECKSUM, TABLE_COLLATION, TABLE_COMMENT, ROW_FORMAT, CREATE_OPTIONS
-
FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;
-
SELECT ORDINAL_POSITION, COLUMN_NAME, COLUMN_TYPE, IS_NULLABLE,
-
COLUMN_DEFAULT, EXTRA, COLUMN_COMMENT, COLUMN_KEY
-
FROM INFORMATION_SCHEMA.COLUMNS
-
WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;
-
SELECT PARTITION_NAME, SUBPARTITION_NAME, PARTITION_ORDINAL_POSITION,
-
SUBPARTITION_ORDINAL_POSITION, PARTITION_METHOD, SUBPARTITION_METHOD,
-
PARTITION_EXPRESSION, SUBPARTITION_EXPRESSION, PARTITION_DESCRIPTION
-
FROM INFORMATION_SCHEMA.PARTITIONS
-
WHERE TABLE_SCHEMA =
’employees’
AND TABLE_NAME =
‘departments’
;