oracle Oracle中表名的最大长度是多少？
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What is the maximum length of a table name in Oracle?
提问by robertkroll
What are the maximum length of a table name and column name in Oracle?
Oracle中表名和列名的最大长度是多少？
回答by TStamper
In Oracle 12.2and above the maximum object name length is 128 bytes.
在Oracle 12.2及更高版本中，最大对象名称长度为 128 字节。
In Oracle 12.1and below the maximum object name length is 30 bytes.
在Oracle 12.1及以下版本中，最大对象名称长度为 30 字节。
回答by TStamper
Teach a man to fish
教人钓鱼
Notice the data-type and size
注意数据类型和大小
>describe all_tab_columns
VIEW all_tab_columns
Name Null? Type
----------------------------------------- -------- ----------------------------
OWNER NOT NULL VARCHAR2(30)
TABLE_NAME NOT NULL VARCHAR2(30)
COLUMN_NAME NOT NULL VARCHAR2(30)
DATA_TYPE VARCHAR2(106)
DATA_TYPE_MOD VARCHAR2(3)
DATA_TYPE_OWNER VARCHAR2(30)
DATA_LENGTH NOT NULL NUMBER
DATA_PRECISION NUMBER
DATA_SCALE NUMBER
NULLABLE VARCHAR2(1)
COLUMN_ID NUMBER
DEFAULT_LENGTH NUMBER
DATA_DEFAULT LONG
NUM_DISTINCT NUMBER
LOW_VALUE RAW(32)
HIGH_VALUE RAW(32)
DENSITY NUMBER
NUM_NULLS NUMBER
NUM_BUCKETS NUMBER
LAST_ANALYZED DATE
SAMPLE_SIZE NUMBER
CHARACTER_SET_NAME VARCHAR2(44)
CHAR_COL_DECL_LENGTH NUMBER
GLOBAL_STATS VARCHAR2(3)
USER_STATS VARCHAR2(3)
AVG_COL_LEN NUMBER
CHAR_LENGTH NUMBER
CHAR_USED VARCHAR2(1)
V80_FMT_IMAGE VARCHAR2(3)
DATA_UPGRADED VARCHAR2(3)
HISTOGRAM VARCHAR2(15)
回答by robertkroll
DESCRIBE all_tab_columns
描述 all_tab_columns
will show a TABLE_NAME VARCHAR2(30)
将显示 TABLE_NAME VARCHAR2(30)
Note VARCHAR2(30) means a 30 byte limitation, not a 30 character limitation, and therefore may be different if your database is configured/setup to use a multibyte character set.
注意 VARCHAR2(30) 表示 30 字节限制，而不是 30 个字符限制，因此如果您的数据库配置/设置为使用多字节字符集，则可能会有所不同。
Mike
麦克风
回答by Maarten
Right, but as long as you use ASCII characters even a multibyte character set would still give a limitation of exactly 30 characters... so unless you want to put hearts and smiling cats in you're DB names your fine...
是的，但是只要您使用 ASCII 字符，即使是多字节字符集仍然会限制 30 个字符...
回答by Wild Pottok
30 char (bytes, really, as has been stated).
30 个字符（字节，真的，如前所述）。
But do not trust me; try this for yourself:
但不要相信我；自己试试这个：
SQL> create table I23456789012345678901234567890 (my_id number);
Table created.
SQL> create table I234567890123456789012345678901(my_id number);
ERROR at line 1:
ORA-00972: identifier is too long
Updated: as stated above, in Oracle 12.2 and later, the maximum object name length is now 128 bytes.
更新：如上所述，在 Oracle 12.2 及更高版本中，最大对象名称长度现在为 128 字节。
回答by Ian Carpenter
The schema object naming rules may also be of some use:
模式对象命名规则也可能有一些用处：
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements008.htm#sthref723
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements008.htm#sthref723
回答by fg78nc
On Oracle 12.2, you can use built-in constant, ORA_MAX_NAME_LEN,
set to 128 bytes (as per 12.2)
Prior to Oracle 12.1max size was 30 bytes.
在 上Oracle 12.2，您可以使用内置常量 ，ORA_MAX_NAME_LEN设置为 128 字节（根据 12.2） 在Oracle 12.1最大大小为 30 字节之前。
回答by Vaibhav
I'm working on Oracle 12c 12.1. However, doesn't seem like it allows more than 30 characters for column/table names.
我正在开发 Oracle 12c 12.1。但是，列/表名称似乎不允许超过 30 个字符。
Read through an oracle page which mentions 30 bytes. https://docs.oracle.com/database/121/SQLRF/sql_elements008.htm#SQLRF00223
通读一个提到 30 个字节的 oracle 页面。 https://docs.oracle.com/database/121/SQLRF/sql_elements008.htm#SQLRF00223
In 12c although the all_tab_columns do say VARCHAR2(128) for Table_Name, it does not allow more than 30 bytes name.
在 12c 中，尽管 all_tab_columns 确实为 Table_Name 说了 VARCHAR2(128)，但它不允许超过 30 个字节的名称。
Found another article about 12c R2, which seems to be allowing this up to 128 characters. https://community.oracle.com/ideas/3338
找到另一篇关于 12c R2 的文章，它似乎允许最多 128 个字符。 https://community.oracle.com/ideas/3338
回答by Harper Shelby
In the 10g database I'm dealing with, I know table names are maxed at 30 characters. Couldn't tell you what the column name length is (but I know it's > 30).
在我处理的 10g 数据库中，我知道表名最多为 30 个字符。无法告诉您列名长度是多少（但我知道它大于 30）。
回答by Annu
The maximum name size is 30 characters because of the data dictionary which allows the storage only for 30 bytes
由于数据字典仅允许存储 30 个字节，因此最大名称大小为 30 个字符
