mysql-查看表结构、建表语句和与oracle的比较(转)

原文地址：http://my.oschina.net/zimingforever/blog/64145

1、查看表结构

desc tableName;
show columns from tableName;
describe tableName;

    这三个显示的结果都是一样的，显示表中filed，type，null，key，default及extra。

--TABLE_SCHEMA表示数据库名称
select * from information_schema.COLUMNS where TABLE_SCHEMA='gm' and TABLE_NAME='t_role';

    这个显示的结果就比较全了。  

2、查看建表语句

   show create table tableName;

3、接下来，来点更全的sql，这个是用来同步mysql和orac数据字典的所有sql。

    mysql部分：

## 查看所有的库
SELECT
    lower(schema_name) schema_name
FROM
    information_schema.schemata
WHERE
    schema_name NOT IN (
        'mysql',
        'information_schema',
        'test',
        'search',
        'tbsearch',
        'sbtest',
        'dev_ddl'
    )
 
## 产看某一个库中的所有表
SELECT
    table_name,
    create_time updated_at,
    table_type,
    ENGINE,
    table_rows num_rows,
    table_comment,
    ceil(data_length / 1024 / 1024) store_capacity
FROM
    information_schema.TABLES
WHERE
    table_schema = 'employees'
AND table_name NOT LIKE 'tmp#_%' ESCAPE '#'
 
##查看某一个库下某一个表的所有字段
SELECT
    lower(column_name) column_name,
    ordinal_position position,
    column_default dafault_value,
    substring(is_nullable, 1, 1) nullable,
    column_type data_type,
    column_comment,
    character_maximum_length data_length,
    numeric_precision data_precision,
    numeric_scale data_scale
FROM
    information_schema.COLUMNS
WHERE
    table_schema = 'employees'
AND table_name = 'employees';
 
 
## 查看某一个库下某一张表的索引
 
SELECT DISTINCT
    lower(index_name) index_name,
    lower(index_type) type
FROM
    information_schema.statistics
WHERE
    table_schema = 'employees'
AND table_name = 'employees';
 
## 查看某一个库下某一张表的某一个索引
 
SELECT
    lower(column_name) column_name,
    seq_in_index column_position
FROM
    information_schema.statistics
WHERE
    table_schema = 'employees'
AND table_name = 'employees'
AND index_name = 'primary';
 
## 查看某一个库下某一个表的注释
SELECT
    table_comment comments
FROM
    information_schema.TABLES
WHERE
    table_schema = 'employees'
AND table_name = 'employees';
 
## 查看某一个库下某一个表的列的注释
SELECT
    lower(column_name) column_name,
    column_comment comments
FROM
    COLUMNS
WHERE
    table_schema = 'employees'
AND table_name = 'employees';

   oracle部分：

#table structure:
SELECT
    lower(table_name) table_name,
    TEMPORARY,
    tablespace_name,
    num_rows,
    duration,
    'ORACLE' table_type,
    partitioned,
    (
        SELECT
            ceil(sum(bytes) / 1024 / 1024)
        FROM
            dba_segments b
        WHERE
            a. OWNER = b. OWNER
        AND a.table_name = b.segment_name
    ) AS store_capacity
FROM
    dba_tables a
WHERE
    OWNER = ?
AND table_name NOT LIKE 'TMP%';
 
SELECT
    lower(column_name) column_name,
    column_id position,
    data_type,
    data_length,
    data_precision,
    data_scale,
    nullable,
    data_default default_value,
    default_length
FROM
    dba_tab_columns
WHERE
    OWNER = ?
AND table_name = ?;
 
# index
SELECT
    lower(index_name) index_name,
    index_type type
FROM
    dba_indexes
WHERE
    OWNER = ?
AND table_name = ?
AND index_name NOT LIKE 'SYS_IL%';
 
SELECT
    lower(column_name) column_name,
    column_position,
    descend
FROM
    dba_ind_columns
WHERE
    table_owner = ?
AND table_name = ?
AND index_name = ?;
 
#collect description
SELECT
    comments
FROM
    dba_tab_comments
WHERE
    OWNER = ?
AND table_name = ?;
 
SELECT
    lower(column_name) column_name,
    comments
FROM
    dba_col_comments
WHERE
    OWNER = ?
AND table_name = ?;
 
#database
SELECT
    lower(username) username
FROM
    dba_users
WHERE
    username NOT IN (
        'STDBYPERF',
        'READONLY',
        'APPQOSSYS',
        'ANYSQL',
        'DBFLASH',
        'SYS',
        'SYSTEM',
        'MONITOR',
        'TBSEARCH',
        'MANAGER',
        'SYSMAN',
        'EXFSYS',
        'WMSYS',
        'DIP',
        'TSMSYS',
        'ORACLE_OCM',
        'OUTLN',
        'DBSNMP',
        'PERFSTAT',
        'SEARCH',
        'TOOLS',
        'TBDUMP',
        'DMSYS',
        'XDB',
        'ANONYMOUS',
        'DEV_DDL'
    );
 
#segsize
SELECT
    round(sum(bytes) / 1024 / 1024, 0) mbytes
FROM
    dba_segments
WHERE
    OWNER = ?
AND segment_name = ?;